Receita Anual Permitida Atinge R$ 538,1

São Paulo, April 29, 2021 - ISA CTEEP - Companhia de Transmissão de Energia El étrica Paulista (“ISA CTEEP,” “Company,” B3: TRPL3 and

TRPL4), announces its results for the first quarter of 2021 (1Q21). Regulatory results are shown in accordance with the Electricity Sector Accounting Manual (MCSE) to facilitate understanding of the Company’s business. Moreover, the information has been prepared in accordance with the standards established by the Securities and Exchange Commission of Brazil (CVM), applicable announcements by the Accounting Statements Committee (CPC) and the International Financial Reporting Standards (IFRS) issued by the International Accounting Standards Board (IASB) in the “Attachments” section of this document.

Main Regulatory Indicators Consolidated (BRL million) 1Q21 1Q20 Var (%) Net Revenue 852.8 734.3 16.1% EBITDA 696.8 597.1 16.7% Adjusted EBITDA¹ 770.4 599.6 28.5% Adjusted EBITDA Margin² 83.2% 81.7% 1.6 p.p. Net Income3 308.1 308.3 -0.05% Net Margin 36.1% 42.0% -5.9 p.p. ROE (amount value of 20.2% 18.4% 1.8 p.p. LTM)

¹Adjusted by the receipt of the Adjustment Portion (PA), excluding the provision and non-recurring effects. ²Considers net revenue adjusted by the PA received. 3Adjusted by non-controlling interest.

CONTENTS

1. ISA CTEEP 1.1 ISA CTEEP 4 1.2 Shareholding Structure 5 1.3 Corporate Structure 6 1.4 Growth 6

2. Operational Performance 7

3. Financial Performance 3,1 Operating Revenue 8 3,2 O&M Costs and Expenses 9 3,3 Equity Income 9 3,4 EBITDA and Margin 10 3,5 Financial Result 11 3,7 Net Income 12 3,8 Comparison of Results (Regulatory vs. IFRS) 13

4. Debt 14

5. Distribution of Earnings 15

6. Investments 15 6.1 Investments in Retrofitting Projects 15 6.2 Investments in Greenfield Projects 16

7. Sustainabiity | ESG Performance 18

8. Capital Markets 19

9. Events during the Period 20

10. Subsequent Events 21

11. Upcoming Events 21

12. Other Relevant Information 22

12. Glossary 26

13. Attachaments 29 * Results in Excel spreadsheet available on the Investor Relations Website

ISA CTEEP ISA CTEEP is Brazil’s largest private electricity transmission company. Through its operations and those of its subsidiaries and affiliate companies, the Company is present in 17 states across Brazil (Rio Grande do Sul, Santa Catarina, Paraná, São Paulo, Minas Gerais, Rondônia, Mato Grosso, Mato Grosso do Sul, Goiás, Tocantins, Maranhão, Piauí, Paraíba, Pernambuco, Alagoas, Espírito Santo and Bahia) and supplies approximately 33% of all electricity transmitted through the National Interconnected System (SIN). The operational control and coordination of the Company’s installations and the entire electricity generation and transmission infrastructure in the SIN are the responsibility of the National Electricity System Operator (“ONS”), subject to inspection and regulations established by ANEEL, the Brazilian electricity regulatory agency. On March 31, 2021, the installed capacity of the Company (including the parent company, wholly-owned subsidiaries and non-consolidated subsidiaries1 in operation) was 68.9 thousand MVA in transformation, 18.8 thousand kilometers of transmission lines, 26.1 thousand kilometers of circuits and 129 own substations. To efficiently operate our complex transmission system, we rely on a team of approximately 1,400 employees and facilities that ensure quality and reliable service.

We are committed to the development of the country’s energy infrastructure and constantly invest on modernizing our network and contributing directly to the expansion of the national transmission system. In recent years, the Company won the bids for 14 lots in the transmission auctions conducted by ANEEL.

1 IE Madeira, IE Garanhuns, IE Aimorés, IE Paraguaçu and IE Ivaí.

Shareholding Structure ISA CTEEP is controlled by ISA, a multi-Latin linear infrastructure systems company.

Shareholders TRPL3 (ON) % TRPL4 (PN) % Total % ISA Capital do 230,856,832 89.50% 5,144,528 1.28% 236,001,360 35.82% Brasil Management 0 0,00% 5,310 0.00% 5,310 0.00%

Free Float 27,080,900 10.50% 395,795,734 98.72% 422,876,634 64.18%

Eletrobras 25,157,077 9.75% 210,692,269 52.55% 235,849,346 35.80%

Others 1,923,823 0.75% 185,103,465 46.17% 187,027,288 28,39%

Total 257,937,732 100.00% 400,945,572 100.00% 658,883,304 100.00%

Base date: 03/31/2021

Total Capital Distribution on 03/31/2021

* Includes the interest held by Isa Capital do Brasil, ISA’s investment vehicle for the acquisition of ISA CTEEP. ** 1% of free float is scattered in other regions.

Excluding the interest held by Eletrobras and ISA, on March 31, 2021, 39% of the shareholder base consisted of foreign investors (22% North America, 15% Europe, 1% Asia and 1% Oceania) and 61% Brazilian investors.

Corporate Structure ISA CTEEP’s corporate structure includes its subsidiaries (wholly-owned subsidiaries) and affiliate companies (subsidiaries not controlled)2, as shown below:

RAP Cycle 2020/2021¹ RAP ISA CTEEP Cycle 2020/2021 Location Profit Regime² Share (%) Consolidation (BRL million) (BRL million)

ISA CTEEP Operational São Paulo 3,131 3,131 Real Profit ISA CTEEP 100% Fully consolidated IE Madeira Operational Rondônia / SP 552 282 Real Profit ISA CTEEP 51% / Furnas 24.5% / Chesf 24.5% Equity method IE Ivaí Under construction Paraná 300 150 Real Profit ISA CTEEP 50% / TAESA 50% Equity method IE Paraguaçu Under construction Bahia / MG 121 61 Real Profit ISA CTEEP 50% / TAESA 50% Equity method IE Garanhuns Operational Pernambuco 95 48 Real Profit ISA CTEEP 51% / Chesf 49% Equity method IE Aimorés Under construction Minas Gerais 81 41 Real Profit ISA CTEEP 50% / TAESA 50% Equity method PBTE Operational São Paulo 172 172 Real Profit ISA CTEEP 100% Fully consolidated IE Riacho Grande Under construction São Paulo 68 68 Presumed Profit ISA CTEEP 100% Fully consolidated IE Pinheiros Operational São Paulo 63 63 Presumed Profit ISA CTEEP 100% Fully consolidated IE Aguapeí Under construction São Paulo 60 60 Presumed Profit ISA CTEEP 100% Fully consolidated IE Serra do Japi Operational São Paulo 56 56 Presumed Profit ISA CTEEP 100% Fully consolidated IE Itaúnas Under construction Espírito Santo 53 53 Presumed Profit ISA CTEEP 100% Fully consolidated IENNE Operational Tocantins 53 53 Presumed Profit ISA CTEEP 100% Fully consolidated IE Itaquerê Operational São Paulo 52 52 Presumed Profit ISA CTEEP 100% Fully consolidated Operational Minas Gerais 20 20 IEMG Presumed Profit ISA CTEEP 100% Fully consolidated Under construction Minas Gerais 33 33 Operational Espírito Santo 13 13 Evrecy Presumed Profit ISA CTEEP 100% Fully consolidated Under construction Rio Grande do Sul 38 38 IE Biguaçu Under construction Santa Catarina 41 41 Presumed Profit ISA CTEEP 100% Fully consolidated SP / Paraná3 21 21 IE Tibagi Under construction Presumed Profit ISA CTEEP 100% Fully consolidated Mato Grosso do Sul / SP 5 5 São Paulo (Bauru) 12 12 IE Itapura Operational Presumed Profit ISA CTEEP 100% Fully consolidated São Paulo (Lorena) 11 11 IE Sul Operational Rio Grande do Sul 20 20 Presumed Profit ISA CTEEP 100% Fully consolidated Total 5,071 4,503 ¹ 2020/2021 revenue cycle includes adjustment portion (“PA”), net of PIS and COFINS. ² Presumed Profit: taxation regime in which income tax is 25% on the presumed 8% of operating income. Social Contribution (CSLL) is 9% on the presumed 12% of operating income. Real Profit: 34% of Income Tax + Social Contribution on calculated taxable income. ³ RAP amount of IE Tibagi does not consider adjustments related to the contractual amendment (-13.5%) approved by the Board of ANEEL on 10/26/20.

Growth

ISA CTEEP’s history is marked by solid growth with sustainable value creation:

¹ ISA CTEEP 51% ² ISA CTEEP 50% ISA CTEEP constantly evaluates growth opportunities in the market and has been making progress in this regard. Its strategy is to expand its footprint across Brazil through auctions and/or acquisitions that are synergistic with existing operations, while respecting the premise of sustainable value generation.

2 IE Madeira, IE Garanhuns, IE Aimorés, IE Paraguaçu and IE Ivaí. 6

In recent years, the Company won the bids for 14 lots in the transmission auctions conducted by ANEEL, for which ANEEL invested (weighted by ISA CTEEP’s stake) a total of BRL6.3 billion, with an increase in RAP (2020/2021 cycle) of around BRL645 million after the assets go operational. Until March 2021, around BRL2.2 billion was invested in these projects. The Company has already energized four of these projects at an average capex efficiency of 36% and 11 months in advance, on average, as shown in the table:

ANEEL’s¹ Investment Investment Made Efficiency Advance Participation ISA CTEEP (BRL million) (%) (months) (BRL milion) Itapura Bauru 63 126 -50% -18 Itaquerê 250 398 -40% -11 Tibagi 118 135 -12% -8 Aguapeí 360 602 -43% -6 Average -36% -11

¹ Amounts on auction date. Another important avenue for growth is the investments made in retrofitting projects. In the last eight years, the Company invested an average of BRL220 million/year on retrofitting Projects in its assets, with associated average RAP of around BRL45 million/year. It must be noted that these are average amounts and the investments may be non-linear as they depend on ANEEL’s authorizations and are subject to the Periodic Tariff Review (“RTP”). The Company has authorizations to invest over BRL1.4 billion on retrofitting projects, which will be executed over the next three years, approximately. The Capex section and Attachment 1 provide more details about growth projects.

OPERATIONAL PERFORMANCE ISA CTEEP is an industry benchmark in performance. The Company constantly manages its operating indicators meticulously, notably the Index of Non-Supplied Energy (IENS), which is the ratio of total energy not supplied during incidents throughout the year to the total energy demanded that the Company did in fact supply. In 1Q21, the Company’s IENS was 0.000083%, compared to 0.000115% in 1Q20. For SIN, IENS was of 0.0032% in January 2021. ISA CTEEP is remunerated through the RAP according to the uptime of its assets. This means that any downtime of its assets may incur a loss of RAP through a discount to verified revenue (Variable Portion – PV). In Mach, 2021, the PV applied was 1.07% of the border and transmission basic network RAP.

FINANCIAL PERFORMANCE (Regulatory Results)

Operating Revenue

In 1Q21, consolidated gross operating revenues were BRL1.0 billion (+BRL148.7 million vs. 1Q20). This result is due to (i) the positive impact of the 2020/2021 RAP cycle, which considers the positive variation of IPCA and the impacts from the application of the Tariff Review; (ii) the operational startup of retrofitting and greenfield projects energized in the last 12 months; and (iii) the conclusion of the acquisition of Piratininga – Bandeirantes Transmissora de Energia (“PBTE “), which is being included in the consolidated financial results of the Company starting from March 2021.

Operational Revenue Consolidated (BRL million) 1Q21 1Q20 Chg (%) Eletric Network Revenue 991.0 843.8 17.5% RBSE 493.8 415.5 18.9% 059 Contract 204.6 223.5 -8.4% CAAE - - - O&M 204.6 223.5 -8.4% Retrofitting Projects (059 Contract) 113.0 102.9 9.9% CAAE 98.2 89.2 10.1% O&M 14.9 13.7 8.5% Bidding Contracts 73.6 48.9 50.4% CAAE 63.6 42.0 51.3% O&M 10.0 6.9 44.9% PBTE 18.1 - - PA, PV and Anticipation 31.7 18.5 71.5% PA (RBSE and RTP) - - - Other PA, PV and Anticipation 31.7 18.5 71.5% Regulatory charges 56.1 34.5 62.6% Others 9.2 7.7 18.8% Gross Revenue 1,000.2 851.5 17.5% Deduction - 147.3 - 117.1 25.8% Net Revenue 852.8 734.3 16.1% Deductions from gross revenue refer to taxes (PIS/COFINS) and regulatory charges (CDE, RGR, R&D, PROINFA, and Inspection Fee), which are transferred to the tariff (gross-up). Deductions totaled BRL147.3 million in 1Q21, up 25.8% from 1Q20, mainly due to the increased revenue from CDE and PROINFRA charges resulting from the year-on-year growth in consumption among free market clients. Note that this effect is neutralized when this amount is transferred to the Electric Energy Trading Chamber (“CCEE”) through deductions. As such, net revenue totaled BRL852.8 million in 1Q21.

O&M Costs and Expenses

O&M Costs and Expenses Consolidated (BRL million) 1Q21 1Q20 Chg (%) Personnel -79.1 -74.9 5.7% Material -3.4 -3.0 12.8% Services -30.0 -30.1 -0.2% Others -19.4 -19.1 1.4% PMSO (ex non-recurring) -131.9 -127.1 3.8% Non-recurring -1.0 -2.5 -60.0% Privat Pension Entity -11.9 - N.A. Contingences 2.0 1.9 4.0% Depreciation -136.9 -140.6 -2.6% Other costs and expenses -147.8 -141.2 4.7% Total -279.7 -268.2 4.3%

O&M costs and expenses (PMSO), purging the non-recurring effects (Covid-19 expenses, growth projects and infraction notice) totaled BRL132.9 million in 1Q21 (+3.8% vs. 1Q20). This result is explained by the: (i) increase in personnel expenses, mainly due to the collective bargaining agreement; (ii) increase in the materials line, mainly due to the acquisition of supplies for the operational teams in response to COVID-19; Other costs and expenses totaled BRL147.8 million, up 4.7% from 1Q20, mainly resulting from the higher expense with the private pension entity due to the recording of provision related to actuarial liabilities of supplementary retirement benefits in compliance with Accounting Pronouncement (CPC) 33. This impact generated an expense of BRL11.9 million in 1Q21, with no cash effect. O&M costs and expenses totaled BRL279.7 million in 1Q21 (+4.3% vs. 1Q20). The Company is focused on financial discipline to neutralize the effect of inflation on costs and expenses.

Equity Income Equity income in 1Q21 was a positive BRL1.2 million (-94% vs. 1Q20). IE Madeira registered a decrease of 43.1% in the quarter due to the reversal of tax provision in 1Q20, which did not repeat in 1Q21, as well as higher financial expense with the increase in financial expenses related to the financial update of the judicial process. IE Garanhuns reported an increase of 15.9% in the quarter mainly due to the better EBITDA. At the pre-operating subsidiaries, the variation is mainly explained by financial expenses resulting from the issue of debentures of IE Ivaí for project funding.

Equity Income (BRL million)

EBITDA and Margin

EBITDA Consolidado (BRL million) 1Q21 1Q20 Chg (%) Net income 852.8 734.3 16.1% Costs and expenses (ex-depreciation) -142.9 -127.7 11.9% Other expenses and operational revenues (ex- -13.1 -9.6 36.8% amortization) EBITDA 696.8 597.1 16.7% Receipt of PA retroactive (RTP and RBSE) 72.6 0.0 - Non-recurring costs and expenses¹ 1.0 2.5 -60.0% Adjusted EBITDA 770.5 599.6 28.5% Adjusted Revenue² 925.4 734.3 26.0% Adjusted EBITDA Margin 83.2% 81.7% 2.0% ¹Considers non-recurring expenses with notice of violation, growth projects and COVID-19 expenses. ²Considers net revenue adjusted by PA (RTP and RBSE).

EBITDA totaled BRL696.8 million in 1Q21, up 16.7% from 1Q20, chiefly due to higher revenue caused by the following factors: (i) the positive impact of the 2020/2021 RAP cycle, which considers the positive variation of IPCA and the impacts from the application of the Tariff Review; (ii) the operational startup of retrofitting and greenfield projects energized in the last 12 months; and (iii) the conclusion of the acquisition of PBTE, which is being included in the consolidated financial results of the Company starting from March 2021. This item was partially offset by the increase in costs with the private pension entity due to the recording of provision related to actuarial liabilities of supplementary retirement benefits in compliance with CPC 33. To reflect the operating cash generation, the Company reports Adjusted EBITDA, which totaled BRL770.5 million in 1Q21, an increase of 28.5% from 1Q20. The adjustment considers the PA amount received (RTP and RBSE) in the period and excludes non-recurring effects to present a more appropriate vision of the Company's operational cash generation. EBITDA from ISA CTEEP’s interest in the non-consolidated subsidiaries IE Madeira and IE Garanhuns totaled BRL58.7 million and BRL10.3 million in 1Q21, respectively. Accordingly, Adjusted EBITDA including Madeira and Garanhuns was BRL839.4 million in the quarter (+24% vs. 1Q20).

Adjusted EBITDA (BRL million)

¹ IE Madeira and IE Garanhuns.

Financial Result The consolidated financial result was an expense of BRL116.2 million in 1Q21, up BRL67.6 million from 1Q20, due to fresh funding (9th and 10th issues of debentures, CCB and BNDES payments) and the lower return from financial investments due to the decline in the CDI rate.

Financial Result Consolidated (BRL million) 1Q21 1Q20 Chg (%) Financial Income 19.8 193.6 -89.7% Financial investment income 9.8 22.0 -55.6% Hedge - 170.1 N.A. Others 10.0 1.5 565.1% Financial Expenses -135.9 -242.2 -43.9% Interest and charges on loans -133.7 -63.1 112.0% Hedge - -176.0 N.A. Others -2.1 -3.1 -31.3% Total (116.2) (48.6) 138.9%

Net Income¹

Net income in 1Q21 was BRL308.1 million, stable in relation to 1Q20.

Net Income (BRL million)

1 Adjusted by non-controlling interest.

Comparison of Results (Regulatory vs. IFRS)

The main variations between the consolidated result through IFRS and regulatory standards in 1Q21 are shown below:

Consolidated DRE (BRL million) IFRS Regulatory Change IFRS vs. Regulatory 1Q21 1Q20

Gross Revenue 1,260 1,000 260 O&M Revenue¹ 318 318 - CAAE Revenue (Annual Cost of Electric Assets)² 0 179 -179 RBSE Revenue 367 494 -127 Infrastructure Revenue 236 0 236

Concession Asset Revenue 312 0 312 Gains in efficiency from implementing 21 0 21 infrastructure Other Revenue 7 9 -2 Deductions -172 -147 -25 Net Revenue 1,088 853 235 Infrastructure Costs -186 0 -186

Costs of O&M and General Expenses -129 -138 8

Costs of Service Provided -5 -5 - Depreciation -5 -137 132 EBIT -325 -280 -45 Equity Income 124 1 123 Amortization of goodwill -1 -1 0 Other Operational Revenues (Expenses) -10 -13 3

Result Before Financial Result and Taxes 761 444 316

Financial Result -116 -116 0 IR & CSLL -176 -134 -42

Net Income before Participation of Non 584 310 274 Controlling Shareholder

Participation of Non Controlling Shareholder -2 -2 0

Consolidated Income/Losses 582 308 274

¹ Considers RAP from O&M, PA, PV, Anticipations and Regulatory Charges of Parent Company and Subsidiaries. ² Considers Annual Cost of Electricity Assets (CAAE) revenue of Parent Company and Subsidiaries.

Revenues: As per IFRS, revenues from investments made during the concession period are booked as construction margin and the setup of discount rate for assets under contract. As per regulatory accounting rules, investments are treated as fixed assets, depreciated according to their useful life and RAP is booked as it is received during the concession period.

Costs: As per IFRS, the costs of implementing infrastructure refer to investments made, calculated as investment plus PIS and COFINS taxes and other charges.

Depreciation: Pursuant to IFRS, the concession asset is not considered a fixed asset but a financial asset or contractual asset. Again, as per IFRS, fixed assets largely relate to assets used by the Company and are not linked to the concession agreement. For Regulatory Result purposes, the concession asset is deemed a fixed asset with its respective depreciation.

Equity Income: The main effects of equity income are the same as for revenue, costs and depreciation explained above.

Income Tax/Social Contribution: As per IFRS, Income Tax/Social Contribution are provisioned monthly on an accrual basis and calculated pursuant to Law 12,973/14. The Company adopts the taxable income method and uses a monthly estimate. The consolidated effective tax rate in 1Q21 was 23% under IFRS and 23% as per Regulatory rules.

DEBT

On March 31, 2021, gross debt reached BRL5,554.5 million, an increase of BRL1,072.3 million from the balance on December 31, 2020, mainly due to the 10th issue of debentures in February 2021 and the recognition of BRL375 million of the debt of PBTE after its acquisition.

The decline in cash and cash equivalents of ISA CTEEP and its wholly-owned subsidiaries in 1Q21 mainly reflects the acquisition of PBTE (BRL1.6 billion), partially offset by the funding carried out to replenish the cash position after the investments made by the Company.

Excluding the cash and cash equivalents of non-consolidated subsidiaries, the Company’s net debt stood at BRL4,231.1 million in March 2021, as against BRL2,332.5 million in December 2020, while the Net Debt/Adjusted EBITDA ratio closed 1Q21 at 1.5 times. DEBT Var 03/31/21 12/31/20 BRL(million) (%) Gross Debt 5,554.5 4,482.2 23.9% Short-term Debt 687.9 312.6 120.1% Long-term Debt 4,866.6 4,169.6 16.7% Consolidated Availabilities+B2 1,679.3 2,520.9 -33.4% Availabilities of ISA CTEEP and Subsidiaries 100% 1,323.4 2,149.7 -38.4% Availabilities of Non-Consolidated Subsidiaries¹ 355.9 371.2 -4.1% Consolidated Net Debt² 4,231.1 2,332.5 81.4% ¹ A part of the Company's funds is invested in exclusive investment funds, which are also used separately by the wholly-owned subsidiaries and non-consolidated subsidiaries (IE Madeira, IE Garanhuns, IE Aimorés, IE Paraguaçu and IE Ivaí), and refer to shares in highly liquid investment funds that are easily convertible into cash, regardless of the maturity of the assets allocated to them. ² Net debt considers cash and cash equivalents of ISA CTEEP and wholly-owned subsidiaries.

The company duly complies with the covenants and requirements for all of its issues. For 2021, the most restrictive Net Debt/EBITDA ratio is 3.0 times. Further details on financial indicators are available in Attachment VII. The average cost of consolidated debt was 8.80% p.a. on March 31, 2021 vs. 7.59% p.a. at December 31, 2020. IPCA is the company’s main index for debt and revenues. Average term of consolidated debt on March 31, 2021 was 7.1 years.

Debt Breakdown Gross Debt Amortization Schedule 03/31/2021 (BRL million)

DISTRIBUTION OF EARNINGS The Bylaws of the Company establish the distribution of a minimum dividend that is the higher of BRL359 million or 25% of net income from the year (IFRS). In June 2018, management informed its dividend practice through a proposal to distribute at least 75% of regulatory net income (used as proxy for cash generation), subject to approval by the Shareholders Meeting, limited to the maximum leverage of 3.0 times Net Debt/EBITDA, and the possibility of paying interim dividends, as envisaged in the Bylaws. On February 22, 2021, the Board of Directors of the Company approved the distribution of dividends amounting to BRL531.2 million, corresponding to BRL 0.806156 per share, which will be paid on May 21, 2021.

INVESTMENTS

ISA CTEEP, its wholly-owned subsidiaries and non-consolidated subsidiaries3 invested BRL290.9 million in 1Q21, BRL13.4 million more than in 1Q20. These variations are mainly explained by the higher authorized investments in retrofitting projects.

(BRL million) 1Q21 1Q20 Var (%) Retroffitings 58.7 7.1 726.8% Greenfield Projects 232.1 270.4 -14.2% Total 290.9 277.5 4.8%

Attachment I details the investments per greenfield project.

Investments in Retrofitting Projects In 1Q21, investments in retrofitting projects totaled BRL58.7 million, an increase of BRL51.6 million from the same period in 2020. The Company has authorizations for 273 projects with ANEEL investments of BRL1.4 billion, which will be executed in the next three years, approximately. In 2021, half of the retrofitting projects in the pipeline should be energized.

3 IE Madeira, IE Garanhuns, IE Aimorés, IE Paraguaçu and IE Ivaí. 15

Investments in Greenfield Projects In the last six years, the Company won the bids for 14 lots in the transmission auctions conducted by ANEEL, for which ANEEL invested (weighted by ISA CTEEP’s stake) BRL6.3 billion, with an increase in RAP (2020/2021 cycle) of around BRL645 million after the assets go operational. The Company has already energized four of these projects (Itapura Bauru, Itaquerê, Tibagi and Aguapeí) at an average capex efficiency of 36% and 11 months in advance, on average. Following are the projects won in the auctions: IE Itapura Interligação Elétrica Itapura S.A. (“IE Itapura”) is responsible for executing Lot 25 won at Auction 015/2016 (“Itapura Bauru”) held by ANEEL in April 2017, and Lot 10 won at Auction 02/2018 (“Itapura Lorena”) held in June 2018. Itapura Bauru is located in the state of São Paulo and involves the installation of a 440 kV (-125/+250) MVAr static compensator in the existing Bauru substation. The installation of this equipment in the substation benefits the SIN as a whole and, especially, voltage control in the 440 kV network in São Paulo. Construction work began in 2Q18 and was completed in 3Q19, when the project obtained the Final Release Statement (TLD) from the ONS for full commercial operation on August 27, 2019 The project was completed with Capex efficiency of 50% and 18 months in advance. Itapura Lorena is responsible for building a substation with a maximum capacity of 1,200 MVA in the city of Lorena in São Paulo, and a 7 km circuit transmission line. In August 2019, the subsidiary obtained the installation license from CETESB for the substation and immediately commenced construction work in 3Q19. Until March 31, 2021, total capex in this project was BRL87 million. IE Itaquerê Interligação Elétrica Itaquerê S.A. (“IE Itaquerê”) is responsible for executing Lot 6 won at Auction 015/2016 held by ANEEL in April 2017. The project is located in São Paulo and includes the installation of three 500 kV (-180/+300) MVAr synchronous compensators in the Araraquara 2 substation (already being operated by State Grid). The installation of this equipment in the substation benefits the SIN as a whole and, especially, provides voltage control for the 440 and 500 kV systems in São Paulo. The subsidiary started construction work in 3Q18. The first equipment was energized in July 2020 and received partial RAP until its conclusion in December 2020. The project was delivered with Capex efficiency of 40% and 11 months in advance. IE Tibagi Interligação Elétrica Tibagi S.A. (“IE Tibagi”) is responsible for executing Lot 5 won at Auction 015/2016 held by ANEEL in April 2017. The project is located in the states of São Paulo and Paraná and involves the installation of a 17 km transmission line and the construction of a substation. The subsidiary obtained the installation license from IBAMA in July 2018 and construction began in 3Q18. The project was delivered in 4Q20 with Capex efficiency of 12% and 8 months in advance. IE Aguapeí Interligação Elétrica Aguapeí S.A. (“IE Aguapeí”) is responsible for executing Lot 29 won at Auction 005/2016 held by ANEEL in April 2017. The project is located in São Paulo and involves the construction of 1,400 MVA substations and the installation of 121 km of transmission lines (140 km circuit). In June 2019, the subsidiary obtained all the installation licenses issued by the São Paulo State Environmental Company (CETESB) and construction work began in 3Q19. Energization took place in 1Q21. The project was delivered six months in advance of ANEEL’s deadline and with a capex efficiency of 40%. IE Itaúnas Interligação Elétrica Itaúnas S.A. (“IE Itaúnas”) is responsible for executing Lot 21 won at Auction 013/2015 held by ANEEL in October 2016. The project is located in the state of Espírito Santo and involves the installation of 79 km of transmission lines, the construction of a substation and the expansion of an existing substation. Expansion works began in 3Q18. The installation licenses for the transmission line and the construction of the substation were issued in August 2019 and works began in 3Q19. Until March 31, 2021, total capex in this project was BRL189.3 million. IE Biguaçu Interligação Elétrica Biguaçu S.A. (“IE Biguaçu”) is responsible for executing Lot 1 won at ANEEL auction 002/2018 held in June 2018. The project is located in Santa Catarina and involves the construction of a 300 MVA substation, expansion of an existing substation and the construction of a 57 km circuit transmission line including overhead, seabed and underground stretches. In 4Q20, the project obtained the Installation License for the Ratones substation and the equipment in the transition zones. The licensing process for the transmission lines was concluded in 1Q21. Until March 31, 2021, total capex in this project was BRL162.5 million. 16

IE Paraguaçu IE Paraguaçu is responsible for executing Lot 3 won at Auction 013/2015 held by ANEEL in October 2016. The Company and Transmissora Aliança de Energia Elétrica S.A. (“Taesa”) each hold 50% interest in the project. The project is located in the states of Bahia and Minas Gerais and involves the installation of 338 km of transmission lines. In May 2019, ISA CTEEP obtained the Installation License from IBAMA for the project and works began in 2Q19. Until March 31, 2021, capex related to ISA CTEEP’s interest in the project totaled BRL232.3 million. IE Aimorés IE Aimorés is responsible for executing Lot 4 won at Auction 013/2015 held by ANEEL in October 2016. The Company and Taesa each hold 50% interest in the project. The project is located in Minas Gerais and involves the installation of 208 km of transmission lines. In April 2019, IBAMA issued the installation license and works began in 2Q19. Until March 31, 2021, capex related to ISA CTEEP’s interest in the project totaled BRL157.4 million. IE Ivaí IE Ivaí is responsible for executing Lot 1 won at Auction 05/2016 held by ANEEL in April 2017. The Company and Taesa each hold 50% interest in the project. The project is located in Paraná and involves the construction of three substations with total capacity of 2,988 MVA, besides the installation of 600 km of double-circuit transmission lines, totaling 1,200 km. Works began in October 2019. Until March 31, 2021, capex related to ISA CTEEP’s interest in the project totaled BRL549.1 million. Minuano Project The Minuano Project is responsible for executing Lot 3 won at Auction 02/2019 held by ANEEL in December 2019. The project is located in the state of Rio Grande do Sul and involves the construction of an 800 MVA substation and 169 km of transmission lines. In 4Q20, the project obtained the installation license for the Caxias Norte substation. The licensing process for the transmission lines is in progress. Until March 31, 2021, total capex in this project was BRL19.4 million. This concession agreement is in the subsidiary Evrecy.

Três Lagoas Project The Três Lagoas Project is responsible for executing Lot 6 won at Auction 02/2019 held by ANEEL in December 2019. The project is located in the states of São Paulo and Mato Grosso do Sul and involves the installation of 37 km of transmission lines and the expansion of two substations. The installation license for the project was obtained in January 2021. Until March 31, 2021, total capex in this project was BRL3.5 million. This concession agreement is in the subsidiary IE Tibagi.

Triângulo Mineiro Project The Triângulo Mineiro Project is responsible for executing Lot 7 won at Auction 02/2019 held by ANEEL in December 2019. The project is located in Minas Gerais and involves the construction of 4 substations with total power of 1,600 MVA, as well as approximately 173 km of transmission lines. The installation license is expected in 3Q21. Until March 31, 2021, total capex in this project was BRL18.1 million. This concession agreement is in the subsidiary IEMG (Interligação Elétrica de Minas Gerais S.A.). Riacho Grande Project The Riacho Grande Project is responsible for executing Lot 7 won at Auction 01/2020 held by ANEEL in December 2020. The project involves the installation of 63 km of 800 MVA transmission lines to supply energy to the Northern, Southern and Eastern regions of the city of São Paulo and the ABC region. The installation license is expected to be obtained in 3Q23.

SUSTAINABILITY | ESG Performance4 ISA CTEEP has been a signatory to the UN Global Compact since 2011 and its commitments are underscored by the Company’s strategy, which is focused on sustainable value generation and responding to global challenges set out in the United Nations (UN) 2030 Agenda. The Company seeks to contribute to the achievement of the Sustainable Development Goals (SDG), primarily focusing on six of them, with alliances and cooperation (SDG 17) as a transverse support axis.

Invests resources and knowledge in favor of new generations through the strategy of private social investment, corporate volunteer program and Connections for Development, one of the Company’s sustainability programs that seeks to strengthen the capabilities of the community ecosystem to drive transformations in its areas of influence.

Contributes through electricity transmission, participating actively in the electricity sector and in the innovation ecosystems, rolling out initiatives to create a society with an innovative infrastructure and which provides welfare and access to energy in a reliable and safe manner for the population. The Company reinforces its commitment to connecting with renewable energy through the issue of green bonds to execute retrofitting and greenfield investments.

“Conexão Jaguar” is one of the Company’s sustainability programs, whose main goals are biodiversity conservation, mitigation of climate change and local development. Currently, it supports one of the regions recognized as a World Heritage Site – the Serra do Amolar region in Pantanal – in the conservation of over 76,000 hectares of preserved area. To learn more, visit https://conexionjaguar.org/pt-br/conexao-jaguar/. ISA CTEEP’s greenhouse gas emission inventory is verified by an independent third-party and recognized with the Gold Seal from the Brazilian GHG Protocol Program. With the revision of the methodology for B3’s Carbon Efficient Index, which extended the invitation to IBRx-100 companies, the Company joined this portfolio in 2021. This recognition demonstrates the Company’s commitment to transparency in its carbon emissions and the transition to a low-carbon economy.

The Company has implemented the Business Ethics and Integrity Program and the Anticorruption Policy, which guide the conduct of employees in their interactions with stakeholders.

Business Sustainability Protection of ecosystems is part of our activities and is included early in the project design stage. We study and select the best routes for transmission lines and substation models that minimize environmental impacts. We strive to ensure that our operations and maintenance activities do not significantly impact biodiversity. To minimize these effects and boost the environmental results of our compensations, we preserve dense stretches of forests to maximize the ecological balance.

4 Environmental, Social and Governance (ESG).

Details of the preservation initiatives and voluntary conservation programs, such as Conexão Jaguar, are available in our 2020 Sustainability Report, audited by an independent third party and published in 1Q21.

COVID-19 ISA CTEEP provides an essential service to society and is committed to and responsible for the health and safety of its stakeholders. The Company has been maintaining the following measures to protect and monitor the impacts of the pandemic: • Adoption of remote work for 100% of the administrative teams; • Assets under construction following all recommended safety protocols; • Periodical monitoring through a multidisciplinary committee, led by senior management; and • Monitoring and promotion of employees’ physical and mental health with the creation of a health channel (available 24 hours) and strengthening of internal communication about COVID-19.

CAPITAL MARKETS ISA CTEEP has its common (“TRPL3”) and preferred shares (“TRPL4”) traded on the São Paulo Stock Exchange (“B3”) and, since 2002, has also been listed on Level 1 of the Corporate Governance segment, valuing ethics and transparency in its relations with shareholders and other stakeholders. The Company’s shares are included in several stock indices, including the Corporate Governance Index, which includes companies with differentiated corporate governance standards, the Brazil 100 Index, which includes companies with the most traded shares on B3, and the Carbon Efficient Index (ICO2), which includes companies that demonstrate greater transparency in reporting their greenhouse gas emissions and how they are preparing for a low carbon economy Moreover, the Company has an American Depositary Receipts (“ADR”) program – Rule 144A in the United States and its ADRs are traded under the tickers “CTPTY” (common shares) and “CTPZY” (preferred shares). The common and preferred shares of ISA CTEEP ended the first quarter of 2021 trading at BRL30.11 and BRL25.33, respectively. The Company’s market capitalization on March 31, 2021, was BRL17.9 billion. Performance of TRPL3, TRPL4 vs. IBOV and IEE (Base 100): 12/31/2020 to 3/31/2021

EVENTS DURING THE PERIOD

Installation License obtained for Três Lagoas project

On January 26, 2021, the Company announced that it obtained the installation license from IBAMA for the Três Lagoas project. With the Installation License obtained, construction works can begin. Click here for details.

Operational startup of IE Aguapeí On February 2, 2021, the Company announced that it energized the Alta Paulista substation (800 MVA) and 105 km of transmission lines, which represent 59% of IE Aguapeí's RAP, six months ahead of the deadline set by ANEEL. Investments in IE Aguapeí totaled about BRL 360 million, over 40% lower than the ANEEL capex. Click here for details.

10th issue of debentures On February 4, 2021, the Board of Directors of the Company approved the 10th issue of simple debentures in a single series. The issue amount is BRL672.5 million and matures in July 2044. Net proceeds from the debenture issue will be used to replenish the Company's cash after the investments made in its assets. Click here for details.

Approval of dividends On February 22, 2021, the Board of Directors of the Company approved the distribution of dividends amounting to BRL531.2 million, corresponding to BRL0.806156 per share. Click here for details.

PBTE

On March 2, 2021, the Company announced the conclusion of the acquisition of PBTE. The PBTE line connects two ISA CTEEP substations (Bandeirantes and Piratininga 2) and started operating in April 2020. The final acquisition price was BRL1,571 million, with net debt of BRL330 million on the baseline date of December 31, 2020. Click here for details.

WACC On March 16, 2021, ANEEL published Order 692/2021 with the Regulatory Capital Remuneration Rate (“WACC”) for the power transmission sector, which declined from 6.96% in 2020 to 6.76% in 2021. The new regulatory WACC will be used in Tariff Reviews during the period from Mar/21 to Feb/22 and the authorizations defined in the period.

Installation License obtained for Biguaçu Project

On March 19, 2021, the Company announced that it had obtained the Installation License for all transmission lines of the Biguaçu project. ANEEL’s investment is BRL641 million and RAP for the 2020-2021 cycle is BRL42 million. Click here for details.

Approval of dividends On March 25, 2021, the Annual Shareholders Meeting approved the distribution of dividends amounting to BRL524.4 million, corresponding to BRL0.795967 per share. Click here for details.

SUBSEQUENT EVENTS

Change in Independent External Auditor

On April 1, 2021, the Company announced, in compliance with Instruction 308 issued by the Securities and Exchange Commission of Brazil (“ICVM 308”), the hiring of Deloitte Touche Tohmatsu Limited as its independent external auditor, replacing Ernst & Young Auditores Independentes S.S. Click here for details.

Operational startup of retrofitting project at Taubaté Substation

On April 5, 2021, the Company announced the operational startup of the retrofitting project at the Taubaté substation. Click here for details.

8th Issue of Commercial Papers

On April 16, 2021, the Company announced the approval of the 8th issue of commercial papers. A total of eight hundred (800) Commercial Papers will be issued at a nominal unit value BRL1.5 billion on the date of issue, totaling BRL1.2 billion, maturing 1,096 calendar days from the date of issue of the Commercial Papers. Click here for details.

Reprofiling of RBSE

On April 22, 2021, the Company announced that ANEEL reprofiled of RBSE to seek alternatives to mitigate the increase in energy tariffs in the 2021/2022 and 2022/2023 cycles, minimizing the impacts for consumers. The Measure ends regulatory discussions spanning almost a decade about payment of RBSE and, although it reflects the gap in the financial flow established in Ratification Resolution 2,714/2020, it preserves the economic value for ISA CTEEP, which will focus on faithfully complying with the payments established, given the importance of this matter to society and its shareholders. Click here for details.

UPCOMING EVENTS

1Q21 Conference Call 10:00 a.m. (BRT) / 9:00 04.30.2021 a.m. (EST) Connection Details:

Brazil: +55 11 4210-1803 / +55 11 3181-8565

Other Countries: +1 412 717-9627 Password: ISACTEEP

Webcast: click here

All data for connection are available in the Investor Relations website: www.isacteep.com.br/ri

OTHER RELEVANT INFORMATION

Annual RAP Adjustment

Ratification Resolution (REH) 2,725 was published on July 15, 2020, establishing new RAPs for ISA CTEEP and its subsidiaries for providing the transmission installations to members of the Basic Network and Other Transmission Installations for a 12-month cycle from July 1, 2020 to June 30, 2021 (2020/2021 cycle). Pursuant to REH 2,725, the RAP and the amounts corresponding to the adjustment portion (PA) of the Parent Company, net of PIS and COFINS, were set at BRL3,131 million for the 2020/21 cycle: i. inflation adjustment5 for the 2019/2020 cycle (IPCA) totaling BRL49 million, which includes BRL29 million related to the portion received from RBSE; ii. operational startup of new retrofitting projects during the 2019/2020 Cycle, which added BRL10 million to the RAP; iii. inclusion once again in the RAP of the “ke” component in the financial component of RBSE, which had been suspended by injunctions; iv. effects of the periodic tariff review, which included a review of the asset base, change of regulatory WACC and definition of a new level for O&M costs, which jointly result in a negative impact of BRL73 million; v. positive adjustment portion of BRL232 million due to the receipt of the first portion (portion 1 of 3) of PA (RTP and RBSE) related to the 2017-2020 retroactive adjustment, in the amount of +BRL303 million, partially offset by the

return of revenue received in advance of -BRL71 million.

The RAP of the Subsidiaries in operation (IEMG, Evrecy, IE Pinheiros, IE Serra do Japi, IENNE, IESUL and Itapura Bauru), net of PIS and COFINS, totaled BRL237 million in the 2020/2021 cycle. The change is due to: i. inflation adjustment for the 2019/2020 cycle totaling +BRL6 million; ii. the outcome of the administrative appeal against REH 2556/19, related to the tariff review of IE Pinheiros and IESUL, entailing a RAP increase of around BRL2 million compared to the results initially pointed out by said REH, partially offset; and iii. the 50% reduction in the RAP for agreement 143/2001 of Serra do Japi, as established in the concession agreement. The RAP and amounts corresponding to the PA of non-consolidated subsidiaries (IE Madeira and IE Garanhuns), net of PIS and COFINS, were BRL647 million in the 2020/2021 cycle. This increase is basically due to the inflation adjustment

¹ IPCA and IGPM from June 2019 to May 2020 were 6.50% and 1.88%, respectively.

during the period and the positive effects of the outcome of the administrative appeal against REH 2556/19 related to the tariff review at IE Madeira.

Below is a summary of the new RAPs for the 2020/2021 cycle, including regulatory charges but net of PIS and COFINS. Parent Company RAP RAP Concessionaire Reinforcements and RAP RAP Contract Index 19/20 Cycle Inflation Ke RTP 20/21 Cycle PA Chg% (BRL million) Improvements 20/21 Cycle1 19/20 Cycle REH 2.565 REH 2.725 ISA CTEEP 1,102 20 10 0 (76) 1,057 232 1,289 1,046 23% 059/2001 IPCA ISA CTEEP - RBSE 1,532 29 0 279 3 1,842 1,842 1,533 20% Total Parent Company 2,634 49 10 279 (73) 2,899 232 3,131 2,579 21%

SUBSIDIARIES (100% ISA CTEEP) RAP RAP Concessionaire Reinforcements and 50% RAP RAP RAP Contract Index 19/20 Cycle Inflation RTP² 20/21 Cycle PA Chg% (BRL million) Improvements Reduction³ 20/21 Cycle1 19/20 Cycle REH 2.565 REH 2.725 Subsidiaries (100%) in operation 529 11 1 2 (5) 538 3 541 350 102% IEMG 004/2007 IPCA 20 0 0 0 0 20 (0) 20 19 5% EVRECY5 020/2008 IGP-M 13 1 0 0 0 13 (1) 13 10 28% 012/2008 11 0 0 0 0 11 0 12 11 7% 015/2008 37 1 1 1 0 39 1 39 35 13% IE PINHEIROS IPCA 018/2008 6 0 0 (0) 0 6 (0) 6 6 -4% 021/2011 6 0 0 0 0 6 (0) 6 5 22% 026/2009 IPCA 43 1 0 0 0 43 (0) 43 42 3% IE JAPI 143/2001 IGP-M 17 1 0 0 (5) 13 (0) 13 16 -18% IENNE 001/2008 IPCA 48 1 0 0 0 49 4 53 46 14% 013/2008 6 0 0 0 0 6 0 6 6 7% IE SUL IPCA 016/2008 13 0 0 1 0 14 1 14 12 19% IE ITAPURA 042/2017 IPCA 12 0 0 0 0 12 (0) 12 12 0% IE ITAQUERÊ 027/2017 IPCA 51 1 0 0 0 52 0 52 51 1% IE TIBAGI 026/2017 IPCA 20 0 0 0 0 21 0 21 20 3% IE AGUAPEÍ 046/2017 IPCA 59 1 0 0 0 60 0 60 59 2% PBTE 012/2016 IPCA 169 3 0 0 0 172 0 172 0 N/A Consolidated ISA CTEEP in operation 3,163 60 11 281 (78) 3,437 236 3,673 2,929 25%

SUBSIDIARIES (equity income) RAP RAP Concessionaire Reinforcements and RAP RAP Contract Index 19/20 Cycle Inflation RTP4 Others Ciclo 20/21 PA Chg% (BRL million) Improvements 20/21 Cycle1 19/20 Cycle REH 2.565 REH 2.725 Subsidiaries (non-consolidated) in operation 624 12 0 13 0 649 (2) 647 602 7% 013/2009 285 5 0 7 0 297 (1) 296 273 9% IE MADEIRA (51% ISA CTEEP) IPCA 015/2009 245 5 0 6 0 255 (0) 255 238 7% IE GARANHUNS (51% ISA CTEEP) 022/2011 IPCA 94 2 0 0 0 96 (1) 95 91 5% Participation ISA CTEEP 318 6 0 7 0 331 (1) 330 307 7%

ISA CTEEP in operation 3,481 66 11 287 (78) 3,768 235 4,002 3,236 24%

SUBSIDIARIES UNDER CONSTRUCTION

RAP RAP Concessionaire Reinforcements and RAP RAP Contract Index 19/20 Cycle Inflation RTP Others Ciclo 20/21 PA Chg% (BRL million) Improvements 20/21 Cycle1 19/20 Cycle REH 2.565 REH 2.725 Subsidiaries (100%) under construction 104 2 0 0 0 181 (0) 181 103 76% IE ITAÚNAS 018/2017 IPCA 52 1 0 0 0 53 0 53 52 3% IE TIBAGI 006/2020 IPCA 0 0 0 0 0 5 0 5 0 N.A. IE ITAPURA 021/2018 IPCA 11 0 0 0 0 11 (0) 11 11 -1% IE BIGUAÇU 012/2018 IPCA 40 1 0 0 0 41 0 41 40 3% EVRECY5 001/2020 IPCA 0 0 0 0 0 38 0 38 0 N.A. IEMG 007/2020 IPCA 0 0 0 0 0 33 0 33 0 N.A. Subsidiaries (non-consolidated) under construction 492 9 0 0 0 501 0 501 491 2% IE PARAGUAÇU (50% ISA CTEEP) 003/2017 IPCA 118 2 0 0 0 121 0 121 118 2% IE AIMORÉS (50% ISA CTEEP) 004/2017 IPCA 79 1 0 0 0 81 0 81 79 2% IE IVAÍ (50% ISA CTEEP) 022/2017 IPCA 294 6 0 0 0 300 0 300 294 2% Participation ISA CTEEP 246 5 0 0 0 251 0 251 246 2%

ISA CTEEP under construction 350 7 - - - 432 (0) 432 349 24%

ISA CTEEP in operation and under construction 3,831 73 11 287 (78) 4,200 235 4,434 3,585 24% ¹ 2020/2021 RAP cycle with PA. ² Considers the outcome of the administrative appeal against REH 2556/19 and the result of RTP for retrofitting projects (REH 2702 and 2705/20). ³ Contract 143 of Serra do Japi establishes a 50% reduction in RAP from November 2019. In the 2019/20 cycle, the impact of the reduction was partial. The 2020/21 cycle is the first with full impact. 4 Considers the outcome of the administrative appeal against REH 2556/19. 5 Includes PIS / COFINS. 6 RAP amount of IE Tibagi does not consider adjustments resulting from the contractual amendment (-13.5%) approved by the Board of ANEEL on October 26, 2020. 7 On December 18, 2020, REH 2826/20 was published, concluding Public Consultation 027/20 on the RTP of IE Serra do Japi’s agreement 026/2009. However, the positive result of RTP of 2.86% will be applied only from July 2021, with retroactive effect from July 2020. On December 23, 2020, an Administrative Appeal was filed with ANEEL regarding the valuation reports of BRR’s assets for agreement 026/2009 of IE Serra do Japi, since the regulatory authority used one of the previous versions of the valuation report in the RTP and did not consider the final version submitted on June 5, 2020. REH 2840, published on 03/30/2021, ratified the result of the analysis of the Administrative Appeal and set the positive tariff repositioning at 2.71%, to be applied from July/21, with retroactive effects.

Concession Renewal – Agreement 059/2001 (RBNI/RBSE)

On September 12, 2012, Provisional Presidential Decree 579/2012 (MP 579) was published regulating the extension of power generation, transmission and distribution concession agreements. According to the Decree, expired concessions or

concessions due to expire within 60 months from its publication had the option to advance their maturity to December 2012 and subsequently extend the respective agreements for up to 30 years.

On November 1, 2012, the Ministry of Mines and Energy (MME) published Interministerial Ordinance 580, which defined the reversal amounts for installations energized from June 1, 2000, that is, the Basic Network of New Installations (“RBNI”). The amount fixed for ISA CTEEP was BRL 2.9 billion. The same date, the MME published Interministerial Ordinance 579, which set the RAP amount for ISA CTEEP at BRL 515.6 million starting from January 1, 2013, which represents a reduction in RAP of approximately 75%.

On November 29, 2012, Provisional Presidential Decree 591 was published authorizing the Concession Authority to pay the amount for undepreciated assets existing prior to May 31, 2000, that is, Basic Existing System Network(“RBSE”).

In December 2012, ISA CTEEP held an Extraordinary Shareholders Meeting to decide on advancing the expiry of Concession Agreement 059/2001 as proposed in PM 579. The Company’s shareholders unanimously approved extending the agreement pursuant to Law 12,783/2013 and the concession was extended to December 2042, guaranteeing the Company the right to receive the amounts relating to the RBNI and RBSE assets.

The amounts related to RBNI, equivalent to BRL 2.9 billion, were received between 2013 and 2015. For the RBSE assets, an independent valuation report was requested to value the investments at the New Replacement Value (“VNR”), adjusted for depreciation up to December 31, 2012. In December 2015, ANEEL approved, through Order 4,036, the value of RBSE assets for ISA CTEEP at BRL 3.9 billion.

In April 2016, MME issued Ordinance 120, which determined that the amounts approved by ANEEL for RBSE facilities be included in the Regulatory Remuneration Base of electricity transmission concessionaires as from the 2017 tariff process for an estimated period of 8 years.

ANEEL Order 1,484/17 of May 2017 redefined the total RBSE amount for ISA CTEEP at BRL 4.1 billion. The initial impact of the RBSE values was the accounting recognition according to IFRS in September 2016 as per the conditions established by MME Ordinance 120. As for regulatory results, the impact on the Company’s numbers is apparent from the initial payments received in July 2017. However, payment of the financial component Ke was suspended in 2017 due to injunctions obtained by some consumers in court.

Starting from November 2019, the courts started dismissing certain lawsuits, which forced the exclusion of Ke from the remuneration on the financial component. ANEEL thus included the remuneration of the financial component by “Ke” in RAP in the 2020-2021 cycle, disregarding the financial effects of late payment, being updated only by the IPCA.

On April 22, 2021, through Homologatory Resolution 2,851/21, ANEEL defined the result of the administrative appeal filed by ISA CTEEP, recognizing the right of the transmission companies to remunerate the portion suspended by injunction and re-profiling the payments of the financial component to from the 2021-2022 cycle. In the new flow, a reduction in the payment curve of the financial component was established for the 2021/2022 and 2022/2023 cycles. In subsequent cycles, the payment flows provided by ANEEL return to levels similar to those approved in Homologatory Resolution 2,714/2020.

The reprofiling occurred due to the economic crisis caused by COVID-19, in which ANEEL looked for alternatives to cushion the increase in energy tariffs in the 2021/2022 and 2022/2023 cycles. The definition presented by ANEEL will contribute to the fair tariff, minimizing the impacts for consumers who are directly affected by the pandemic. It is worth mentioning that, despite the mismatch in the financial flow established in Homologatory Resolution 2,714/2020, the decision of the Collegiate Board of ANEEL preserves the economic value for ISA CTEEP, since the premises to be valid from the 2021/2022 cycle onwards were: (i) the completion of the payment of the financial component of RBSE by the cycle 2027/2028; (ii) the reduction in debt amortization with the financial component of RBSE without an effect on the increase in the balance payable; and (iii) the remuneration for the regulatory WACC defined in the 2018 RTP.

Older Flow of Receipts of RBSE (BRL million)

Note: The graph shows amounts defined for the revenue cycles 2017/2018 (REH ANEEL 2,258), 2018/2019 (REH ANEEL 2,408), 2019/2020 (REH ANEEL 2,565) and 2020/2021 (REH ANEEL 2,725). Assumptions for future cycle as per REN ANEEL 762/2017 and based on the worksheets published at the end of CP 22/2020. Nominal values – base date: June 2020

New Flow of Receipts of RBSE (BRL million)

Supplementary Retirement Plan – Law 4,819/58 The supplementary retirement plan is governed by State Law 4,819/58 and applies to employees hired prior to May 13, 1974, by government agencies and corporations in which the state of São Paulo is the controlling shareholder and exercises control.

The funds needed to meet the costs under this plan are the responsibility of the São Paulo State Government and the plan was implemented as per the agreement between the Tax Authority of the State of São Paulo (SEFAZ) and the Company on December 10, 1999. Payments of the supplementary retirement benefits are made monthly by SEFAZ. SEFAZ transferred the amount to be paid to ISA CTEEP, which then transferred it to Fundação CESP to be paid to individual retirees.

Since January 2004, retiree benefits have been processed directly by SEFAZ. This change in the process revealed disallowances such as payments in excess of the ceiling (equivalent to the State Governor’s salary). As a result, SEFAZ started excluding the surplus amounts from the benefits paid to retirees.

Public-Interest Civil Action and Class Action

In June 2005, after the courts dismissed a claim, the Funcesp Retirees Association (“AAFC”) obtained an injunction in the Labor Court, which ordered the maintenance of the previous payment in full. The benefits payment process has since reverted to the original model, where Fundação CESP was responsible for retirement payments. However, SEFAZ continues to transfer the adjusted amount to ISA CTEEP, which then adds the difference so that retirement payments are made in full, as ordered by the injunction.

Collection Lawsuit Since 2005, SEFAZ has been transferring to the Company amounts lower than required to make full payment (about 70%) to the retirees following an injunction by the 49th Labor Court. ISA CTEEP has since been making up the difference to ensure full payment of retiree benefits (about 30%). The difference paid by ISA CTEEP is being claimed in a collection lawsuit filed against SEFAZ.

The São Paulo Court of Appeals ruled in the Company’s favor. In August 2017, SEFAZ filed a special appeal at the Federal Court of Appeals (STJ), which is awaiting the analysis of admissibility. On March 31, 2021, the amount booked in the Company’s balance sheet was approximately BRL2.3 billion, net of provisions for losses on the realization of credits in 2013.

In August 2018, ISA CTEEP obtained a ruling from the São Paulo Court of Appeals requiring SEFAZ to refrain from disallowing any transfers concerned with the payment of benefits under Law 4,819/58 before concluding the administrative proceedings to check for irregular payments. In March, the Federal Court of Appeals, in an interim individual ruling by Justice Francisco Falcao, suspended the effects of the injunction that prohibited São Paulo State Finance Department from making deductions in its payments to ISA CTEEP. The Company once again received the transfer with the disallowances, forcing it to supplement the amount paid in April 2019.

The Company continues its efforts to uphold the favorable ruling given by the São Paulo Court of Appeals.

GLOSSARY Brazilian Electricity Regulatory Agency (ANEEL) - Agency entrusted with regulating and supervising the generation, transmission, distribution and sale of electricity in Brazil, ensuring the quality of services provided, the fair treatment of users and controlling the reasonableness of tariffs charged to consumers, while maintaining economic and financial viability of the players and the sector. ANEEL inspects and regulates access to transmission systems and establishes the tariffs for such systems, including TUST, which is the tariff charged for the use of the Basic Network and Other Transmission Installations (DIT).

CAAE (Annual Cost of Electricity Assets) – Revenue from investments in assets. It consists of the remuneration on capital and the regulatory reintegration quota (QRR)

CAOM (Management, Operating and Maintenance Costs) - Portion of revenue that can be divided into (i) revenue from O&M, which is used to bear the costs and expenses (e.g.: wages, maintenance expenses and others); and (ii) revenue to pay for costs of movable and fixed installations (CAIMI).

CDE (Energy Development Account) - regulatory charge to ensure the universal supply of energy and subsidize low- income consumers.

DIT (Other Transmission Installations) - Installations with voltage lower than 230 kV.

EBITDA - Earnings Before Interest, Taxes, Depreciation & Amortization.

Electric Energy Trading Chamber (CCEE) - Operating under the authorization of the government, and regulated and supervised by ANEEL, its mission is to promote the purchase and sale of electricity among its members.

Energization - operational startup of a project (retrofit or greenfield).

Energy Transmission Auctions - Auctions held by MME and ANEEL to grant concessions for transmission lines and substations in Brazil.

EPE (Energy Research Company) - Federal government agency linked to the Ministry of Mines and Energy. Responsible for national energy planning, including generation, transmission, distribution, oil and gas.

Greenfield - projects to achieve growth through auctions.

IEE (Electric Utilities Index) - B3 stock exchange index that measures the performance of the electricity sector.

MME –Brazil’s Ministry of Mines and Energy

National Electricity System Operator (ONS) - Brazilian agency responsible for coordinating and controlling power generation and transmission operations in the SIN.

O&M - Operation and Maintenance.

Organic growth - growth through investments in retrofitting projects.

Other revenues - Revenues from non-concession operations, partly intended to enable lower tariffs.

PA (Adjustment Portion) - Offsets the funding surplus or deficit in the period prior to the adjustment.

PROINFA - Incentive Program for Alternative Electricity Sources (regulatory charge for subsidies to alternative energy sources).

PV (Variable Portion) - Penalizes revenue from asset due to unavailability.

RAP (Permitted Annual Revenue) - Remuneration received by transmission companies for providing public transmission services to users. For transmission companies that won auctions, RAP is obtained as a result of the transmission auction itself and is paid to them upon the operational startup of their installations, and is reviewed every four or five years as per the concession agreements. For transmission companies whose concession agreement was renewed, RAP was calculated based on the Operation and Maintenance costs, pursuant to Law 12,783 of January 11, 2013. In cases where studies indicate the need for reinforcements in the transmission concession, ANEEL calculates an additional amount for RAP to remunerate new installations, always through an Authorizing Resolution.

RB (Basic Network) - SIN transmission installations owned by public transmission services concessionaires, defined according to the criteria established in ANEEL regulations.

RBNI (Basic Network New Investments) - Portion of revenue (RAP) corresponding to the new authorized installations of the Basic Network, whose revenues are established by a specific resolution.

RBSE (Basic Network of Existing System) - Portion of RAP corresponding to installations in the Basic Network, defined in the Appendix to Resolution 166 of May 31, 2000.

Regulatory Charges - these are charged by transmission companies and passed on to CCEE, ANEEL and MME, and also invested in R&D projects. These have a neutral effect on the transmission company.

Retrofitting Project - includes the installation, replacement or refurbishment of equipment in existing transmission facilities or adaptations made in these facilities to maintain the regularity, continuity, safety and timeliness of the public electricity transmission services, or adaptations made to these facilities to expand transmission capacity, increase the reliability of the National Interconnected System, the useful life or connection of users, as recommended by the transmission system expansion plans.

SIN (National Interconnected System) - All the installations and equipment that supply electricity to regions across the country, which are electrically interconnected according to applicable regulations.

TUST (Electricity Transmission System Usage Tariff) - Tariff paid by distributors, generators and free and special consumers for use of the Basic Network and DIT, and is adjusted annually according to (i) inflation; and (ii) new revenues from energized projects.

ATTACHMENTS

Attachment I - Greenfield Projects

ANEEL CAPEX Implementation RAP ISA CTEEP Entry in % ISA ISA CTEEP Contract Deadline ANEEL Environmental Initiation of Land Projects Auctions Subsidiaries Location Discount Cycle 2020/2021 Necessity Date¹ Commercial CTEEP Participation signature License (LI) Construction Development4 Development5 (BRL MM) ANEEL Operation (BRL MM) IE Paraguaçú Bahia 50% 255 0.0% 61 Feb-17 Feb-22 Jan-19 2Q19 100% 87% - (Lot 3) Minas Gerais ✓ Auction IE Aimorés 013/2015 50% Minas Gerais 171 0.0% 41 Feb-17 Feb-22 Jan-19 2Q19 99% 90% - (Lot 4) ✓ 10/28/2016 IE Itaúnas 100% Espírito Santo 298 25.1% 53 Feb-17 Feb-22 Jul-18 3Q18 100% 68% - (Lot 21) ✓ IE Ivaí 50% Paraná 968 33.2% 150 Aug-17 Aug-22 Feb-21 4Q19 91% 72% - (Lot 1) ✓ IE Tibagi6 São Paulo 100% 135 32.2% 21 Aug-17 Aug-21 Jan-17 3Q18 100% 100% 4Q20 Auction (Lot 5) Paraná ✓ 05/2016 IE Itaquerê 100% São Paulo 398 44.5% 52 Aug-17 Aug-21 Jun-18 3Q18 100% 100% 3Q20 4/24/2017 (Lot 6) ✓ IE Aguapeí 100% São Paulo 602 52.7% 60 Aug-17 Aug-21 Dec-18 3Q19 100% 100% 1Q21 (Lot 29) ✓ IE Itapura São Paulo 100% 126 57.6% 12 Aug-17 Feb-21 Aug-19 2Q18 100% 100% 3Q19 (Lot 25) (Bauru) ✓ IE Itapura São Paulo Auction 100% 238 73.9% 11 Sep-18 Sep-22 Jan-20 3Q19 100% 90% - (Lot 10) (Lorena) ✓ 02/2018 IE Biguaçu 06/29/2018 100% Santa Catarina 641 66.7% 41 Sep-18 Sep-23 Sep-21 1Q21 64% 57% - (Lot 1) ✓ Minuano Rio Grande do 100% 682 66.9% 38 Mar-20 Dec-24 Jan-20 3Q21 - 28% 28% - (Lot 1) Sul Auction Mato Grosso do Três Lagoas 02/2019 100% Sul 99 68.1% 5 Mar-20 Jun-23 Jan-20 1Q21 72% 36% - (Lot 6) ✓ 12/19/2019 São Paulo Triângulo Mineiro 100% Minas Gerais 554 65.4% 33 Mar-20 Dec-24 Jan-20 3Q21 - 60% 24% - (Lot 7) Auction 01/2020 Riacho Grande 100% São Paulo 1,141 57.9% 68 Mar-21 Dec-25 Jan-26 3Q23 - - 4.1% - 12/17/2020 (Lot 7) Total 6,306 645 ¹According to the concession agreement. | ²To receive the total RAP amount. | 3Land Development: evolution of properties released. | 4Project Development: evolution of all activities related to the project until its energization. | 5RAP amount of IE Tibagi does not consider adjustments resulting from the contractual amendment (-13.5%) approved by the Board of ANEEL on October 26, 2020. | 6Partial installation license (LI) obtained.

Investments (BRL Million) 1Q21 1Q20 Chg (%) Retroffiting Projects 58.8 7.1 727.7% Greenfield Projects 232.1 270.4 -14.2% Aguapeí 35.8 87.2 -58.9% Aimorés 1.9 40.1 -95.2% Biguaçu 45.5 1.9 2333.0% Itapura 12.3 22.1 -44.5% Itaquerê 0.2 1.0 -75.9% Itaúnas 11.6 17.1 -32.5% Ivaí 102.3 34.4 197.8% Minuano 8.8 0.0 N.A. Paraguaçu 2.1 62.0 -96.7% Tibagi 2.3 4.6 -50.6% Três lagoas 1.3 0.0 N.A. Triângulo Mineiro 7.9 0.0 N.A. Total 290.9 277.5 4.8%

Note: Considers ISA CTEEP’s 50% interest in non-consolidated subsidiaries.

Attachment II – Regulatory Balance Sheet Assets Consolidated

(BRL thousand) 03/31/2021 12/31/2020

CURRENT Cash and Cash Equivalents 853,688 2,067,337 Financial Investments 469,733 453,557 Accounts receivable - Concessionaires and Permissionaires 692,135 658,932 Inventory 20,707 22,652 Services in course 19,330 22,259 Recoverable taxes and contributions 72,195 28,807 Derivative instruments 7,507 12,368 Credit with controlled parties 14,771 5649 Prepaid Expenses 36,595 6,400 Restricted cash 3,873 1,808 Others 56,067 69,415 2,246,601 3,349,184 NON-CURRENT Long-Term Assets Restricted cash 40,249 46,903 Accounts receivable - Concessionaires and Permissionaires 417,349 498,309 Accounts Receivable from the State Finance Secretariat 1,821,503 1,778,999 Deferred income taxes and social contribution 41,074 0 Pledges and Escrow 47,184 44,119 Derivative instruments 18,417 226 Ongoing service 11,984 7,538 Others 102,146 102,772 2,499,906 2,478,866 Investments 1,537,544 1,517,335 Imobilized 8,330,318 7,912,308 Intangible 1,918,001 359,753 11,785,863 9,789,396 14,285,769 12,268,262 Total Assets 16,532,370 15,617,446

Liabilities and Shareholders' Equity Consolidated (BRL thousand) CURRENT Loans and Financing 461,788 94,628 Debentures 245,489 217,948 Leasing 81 81 Derivative financial instruments 0 2,578 Suppliers 100,371 153,346 Taxes and social charges to be collected 268,737 255,614 Deferred Income Tax and Social Contribution 67,260 0 Regulatory charges to be collected 44,836 49,457 Interest on Shareholders' Equity / Dividends to pay 1,068,548 500,513 Provisions 36,212 45,094 Amounts Payable - Funcesp 855 871 Special obligations - Reversal/Amortization 2,480 2,480 Adjustment Parcel 3,947 0 Others 56,916 43,743 2,357,520 1,366,353 NON-CURRENT Long-Term Liabilities Loans and Financing 1,182,886 1,208,301 Debentures 3,664,357 2,961,318 Leasing 0 18 Employee Benefit - Actuarial Deficit 394,078 381,978 Diferred PIS and COFINS 65,790 71,465 Deferred income taxes and social contribution 868,910 913,557 Regulatory charges to be collected 50,331 48,065 Provisions 126,098 85,736 Global Reversal Reserve - RGR 13,512 14,132 Obligations connected to concession service 397,485 380,135 Others 11,973 54,032 6,775,420 6,118,737 SHAREHOLDER'S EQUITY Share Capital 3,590,020 3,590,020 Capital Reserves -18,380 -18,380 Income Reserves 5,137,515 1,192,077 Revaluation reserve 2,083,781 2,136,052 Actuarial surplus -364,659 -364,659 Other Comprehensive Results 166,602 140,114 Accumulated Profits and Losses -3,551,375 1,085,973 7,043,504 7,761,197 Non-controlling shareholders' share of investment funds 355,926 371,159 7,399,430 8,132,356 Total Liabilities and Shareholders' Equity 16,532,370 15,617,446

Attachment III – Regulatory Income Statement

Income Statement Consolidated (BRL thousand) 1Q21 1Q20 Chg (%) Gross Revenue 1,000,176 851,478 17.5% Availability of Electric Network 991,025 843,755 17.5% Others 9,151 7,700 18.8% Deductions from the Operational Revenue -147,343 -117,137 25.8% Net Revenue 852,857 734,341 16.1% Costs and Operational Expenses - 279,729 - 270,109 3.6% Personnel -91,145 -74,866 21.7% Material -3,689 -3,005 22.8% Services -30,613 -30,082 1.8% Depreciation -136,891 -140,551 -2.6% Others -17,391 -21,605 -10.4% Result of Service 573,105 466,129 22.9% Financial Results -116,197 -48,618 139.0% Income from Financial Investments 9,761 21,983 -55.6% Result of Liquid Monetary Variation -68,620 -26,159 162.3% Asset and Liability Interest 908 -418 -317.2% Interest/Charges on loans -62,773 -36,389 72.5% Others 4,527 -7,635 -159.3% Operational Result 456,908 417,511 9.4% Equity Income 1,214 20,314 -94.0% Other Operational Revenues/Expenses -13,717 -10,187 34.7% Results before Taxes 444,401 427,638 3.9% Income Tax and Social Contribution on Income -134,410 -103,852 29.4% Current -210,719 -77,594 171.6% Deferred 76,309 -26,258 -390.6% Consolidated Income/Losses of the Period with the Participation of the Non-Controlling 309,991 323,786 -4.3% Shareholder Participation of Non Controlling Shareholder -1,855 -15,497 -88.0% Net Income/Loss Consolidated in the Period 308,136 308,289 0.0%

Attachment IV – Indirect Cash Flow – Regulatory

Cash Flow of operational activities Consolidated

3/31/2021 12/31/2020 Cash generated by operational activities 486,103 3,133,131 Net Income 309,991 2,023,537 Employee benefit - actuarial deficit 12,100 15,368 Deferred PIS and COFINS -5,798 71,465 Depreciation and amortization 136,891 573,048 Deferred income taxes and social contribution -76,309 153,387 Provision for Lawsuit Liabilities -1,533 8,085 Residual value of fixed/intangible assets 3,059 40,234 Tax benefit - incorporated goodwill 9 37 Realization of concession assets in the acquisition of subsidiary 598 (6,531) Realization of the loss in jointly controlled -1,187 (1,812) Result of acquisition of control 0 0 Result of equity income -1,209 60,434 Income from financial investments -655 (4,437) Interest and exchange variations on loans, financing and debentures 96,539 0 Interest and monetary and exchange variations on assets and liabilities 13,607 200,316 Assets Variation (22,486) (1,210,110) Restricted cash 4,589 (156) Accounts receivable - Concessionaires and Permissionaires 65,040 (889,884) Inventories 1,945 (7,710) Accounts Receivable from the State Finance Secretariat -42,504 (202,667) Recoverable taxes and contributions -31,187 3,528 Prepaid Expenses -30,195 (1,723) Pledges and Escrow -2,861 9,856 Services in course 0 (3,890) Credit with subsidiaries -9,122 9,387 Others 21,809 (126,851) Liabilities Variation (42,020) 185,567 Suppliers -55,505 (14,428) Taxes and social charges to be collected 8,272 163,522 Labor obligations -8,882 11,753 Taxes in installments - 0 Regulatory charges to be collected -2,583 6,665 Provisions -4,742 11,778 Amounts Payable - Funcesp -16 (1,302) Global Reversal Reserve - RGR -620 (2,480) Obligations related to concession of service 17,350 28,091

Others 4,706 (18,032) Net cash generated in operational activities 421,597 2,108,588 Investments Activites Cash Flow (1,798,477) (936,760) Financial Investments -265,886 (1,744,485) Redemptions of financial investments 235,132 1,767,685 Fixed Assets -177,658 (758,153) Intangible -30,479 (758,153) Investments -1,590,065 (221,501) Cash acquired in business combination 67,555 0 Received dividends 0 19,694 Cash used in financing activities 126,155 299,538 New loans 672,500 2,255,516 Loan payments (principal) -31,807 (1,263,352) Loan payments (interest) -35,977 (167,144) Lease Payments (principal and interest) -195 (308) Lease Payments (interest) 0 0 Transactions with non-controlling shareholders -1,855 (21,147) Derivative instruments 11,067 243,342 Capital payment 0 0 Paid dividends and interest on equity -487,578 (747,369) Net variation in Cash and Cash Equivalents -1,250,725 1,471,366 Opening Balance of Cash and Cash Equivalents 2,067,337 595,971 Closing Balance of Cashand Cash Equivalents 853,688 2,067,337 Closing Balance of Cash and Cash Equivalents (1,213,649) 1,471,366

Attachment V - Regulatory Results of Non-Consolidated Subsidiaries (IE Madeira and IE Garanhuns) IE MADEIRA Income Statement (BRL million) 1Q21 1Q20 Chg (%)

Gross Operational Revenue 152,703 144,812 5.45% Operational Revenue Deductions -20,572 -18,431 11.62% Net Operational Revenue 132,131 126,381 4.55% Costs and Expenses -9,775 867 -1227.45% Depreciation -36,790 -33,859 8.66% EBITDA 115,079 127,488 -9.73% Gross Profit 85,566 93,389 -8.38% Financial Result -43,687 -35,418 23.35% Other Revenues and Expenses -7.277 241 -103.02% Income before IR & CSLL 34,602 58,212 -40.56% IR & CSLL* -1,616 -290 457.24% Net Income 32,986 57,922 -43.05%

ISA CTEEP Participation (51%) on EBITDA 58,690 65,019 -9.73% ISA CTEEP Participation (51%) on Net Revenue 16,823 29,540 -43.05%

IE GARANHUNS Income Statement (BRL million) 1Q21 1Q20 Chg (%)

Gross Operational Revenue 27,548 26,233 5.01% Operational Revenue Deductions -3,610 -3,412 5.80% Net Operational Revenue 23,938 22,821 4.89% Costs and Expenses -3,655 -3,537 3.34% Depreciation -6,244 -6,253 -0.14% EBITDA 20,280 19,443 4.30% Gross Profit 14,039 13,031 7.74% Financial Result -2,597 -3,047 -14.77% Other Revenues and Expenses -3 159 -101.89% Income before IR & CSLL 11,439 10,143 12.78% IR & CSLL* -444 -655 -32.21% Net Income 10,995 9,488 15.88%

ISA CTEEP Participation (51%) on EBITDA 10,343 9,916 4.30% ISA CTEEP Participation (51%) on Net Revenue 5,607 4,839 15.88%

(*) Has an infrastructure project consisting of transmission lines and an electricity substation operating in areas covered by SUDENE, whose benefit was granted in December 2016. The period for enjoying the tax benefit, which is a 75% reduction in income tax and surcharges, is 10 years.

Attachment VI – Breakdown of Consolidated Debt (BRL thousand) Funding Charges Maturity 3/31/2021 12/31/2020 BNDES TJLP + 1.80% per year 03/15/29 154.2 159.1 3.50% per year 01/15/24 28.9 31.5 TJLP + 2.62% per year 03/15/32 214.0 218.9 CTEEP - Debentures 4th Issuance IPCA + 6.04% 07/15/21 183.6 176.5 5th Issuance IPCA + 5.04% 02/15/24 348.4 352.5 7th Issuance IPCA + 4.70% 04/15/25 707.6 682.0 8th Issuance IPCA + 3.50% 12/15/29 421.7 407.0 9th Issuance CDI + 2,83% 11/15/28 805.4 795.7 9th Issuance IPCA + 5,3000% per year 05/15/44 796.0 765.5 10th Issuance IPCA + 5,0700% 17/072025 647.3 - CTEEP - Others Law 4,131 - MUFG VC + 3.34% per year + IR 07/20/20 - - Law 4,131 - Citibank VC + Libor 3M + 0.47% per year + IR 08/24/20 - - Law 4,131 - Citibank VC + Libor 3M + 0.25% per year + IR 11/08/2019 - - CCB CDI + 2.45% per year 04/20/22 652.9 653.3 CTEEP Total Gross Debt 4,959.9 4,242.0 Funding Charges Maturity 03/31/21 12/31/20 PINHEIROS TJLP + 2.06% per year 02/15/28 3.8 3.9 3.5% per year 04/15/23 3.8 4.2 TJLP + 2.62% per year 05/15/26 18.6 19.5 5.5% per year 01/15/21 0.0 0.8 SERRA DO JAPI TJLP + 1.95% per year 05/15/26 19.9 20.9 TJLP + 1.55% per year 05/15/26 17.2 18.0 IEMG TJLP + 2.39% per year 04/15/23 (0.0) 12.3 IE SUL 5.5% per year 01/15/21 (0.0) 0.1 TJLP + 2.58% per year 05/15/25 3.2 3.4 3.0% per year 04/15/23 2.5 2.8 TJLP + 2.58% per year 02/15/28 5.9 5.9 IENNE 8.5% per year 05/19/30 145.1 148.2 PBTE CDI + 1.60% 20/07/21 374.8 - Subsidiaries Total Gross Debt 594.8 240.2 Consolidated Total Gross Debt (BRL thousand) 5,554.5 4,482.1

BNDES Infrastructure Debentures (annual verification) (4th and 5th issuance) (quarterly verification) Net Debt 03/31/2021 5.719 Net Debt 03/31/2021 4.282 EBITDA last 12 months 2.792 EBITDA last 12 months 2.696 Net Debt/EBITDA 2.05 Net Debt/EBITDA 03/31/2021 1.59 03/31/2021 Shareholders' Equity 13.664 Financial Result 03/31/2021 276 03/31/2021 Net Debt/Net Debt + EBITDA/Financial Result Shareholders' Equity 0.30 9.78 03/31/2021 03/31/2021

The main covenants that ISA CTEEP must comply with are: The financing agreements with BNDES (valid until the expiry of the agreement in 2029) must meet the following maximum financial indicators: Net Debt/BNDES Adjusted EBITDA ≤ 3.0 and Net Debt/(Net Debt + Shareholders’ Equity) ≤ 0.6 at the end of each fiscal year. For the purposes of calculating and substantiating these indices, the Company must consolidate all subsidiaries and joint ventures (in proportion to its interest) provided its interest is 10% or higher. The 4th issue of debentures must meet the quarterly calculation frequency and the financial indicators established in the indenture: Net Debt/EBITDA < 3.5 and EBITDA/Financial Result > 1.5 until the baseline date of June 30, 2017 and, after the baseline date of September 30, 2017, the indicator is > 2.0. EBITDA is calculated according to the methodology defined in the agreement. The 5th issue of debentures must meet the quarterly calculation frequency and the financial indicators established in the indenture: Net Debt/EBITDA < 3.5 and EBITDA/Financial Result > 1.5 until the baseline date of June 30, 2017 and, after the baseline date of September 30, 2017, the indicator is > 2.0. EBITDA is calculated according to the methodology defined in the agreement.

Attachment VII – Breakdown of Debt of Non-consolidated Subsidiaries - IE Madeira, IE Garanhuns e IE Ivaí (BRL thousand)

Amount Total Amount Final Company Bank Charges guaranteed Owed Maturity by ISA CTEEP 03/31/2021

IE MADEIRA ITAÚ IPCA + 5.5% per year 03/18/2025 190.8 374.0

51% ISA CTEEP BNDES TJLP + 2.42% per year 02/15/2030 495.3 971.2

BNDES TJLP 02/15/2030 3.4 6.7 BNDES 2.5% per year 10/15/2022 33.6 65.9 BASA 8.5% per year 10/10/2032 149.4 292.8 Gross Debt 872.5 1710.7 Availability 192.6 377.6 Net Debt 494.8 1518.1 IE GARANHUNS BNDES TJLP + 2.05% per year 12/15/2028 65.5 128.3

51% ISA CTEEP BNDES 3.50% per year 08/15/2023 25.1 49.2

BNDES TJLP 12/15/2028 0.5 0.9 Gross Debt 91.0 178.5 Availability 11.6 22.7 Net Debt 68.4 166.9 IE IVAÍ ITAÚ BBA IPCA + 5.0% per year 12/15/2043 897.4 1759.6 50% ISA CTEEP

Gross Debt 897.4 1759.6 Availability 807.3 411.7 Net Debt 90.1 1347.9 TOTAL Gross Debt 1860.9 3648.8 TOTAL Net Debt 653.3 3033.0

Attachment VIII – Balance Sheet under IFRS Assets Consolidated

(BRL thousand) 3/31/2021 12/31/2020

CURRENT Cash and cash equivalents 853,688 2,067,337 Financial investments 469,733 453,557 Concession Asset 3,057,083 2,804,373 Inventories 49,717 45,297 Taxes and contributions to compensate 72,195 28,807 Derivative instruments 7,507 9,790 Credit with related parties 14,771 14,994 Prepaid expenses 36,595 6,400 Restricted Cash 3,873 1,808 Others 66,824 75,495 4,631,986 5,507,858 NON-CURRENT Long-term Receivables Restricted Cash 40,249 46,903 Concession Asset 16,221,607 14,167,152 Accounts Receivable from the State Finance Secretariat 1,821,503 1,778,999 Pledges and Escrow 47,184 44,119 Inventories 12,634 9,997 Derivative instruments 18,417 226 Others 114,129 110,310 18,275,723 16,157,706 Investments 3,001,178 2,928,478 Imobilized 90,195 92,991 Intangible 506,317 24,499 3,597,690 3,045,968 21,873,413 19,203,674 Total Assets 26,505,399 24,711,532

Liabilities and Shareholders' Equity Consolidated (BRL thousand) CURRENT Loans and financing 461,788 94,628 Debentures 245,489 217,948 Leasing 7,816 8,795 Derivative instruments 100,371 153,346 Suppliers 268,737 255,614 Taxes and social charges to be collected 44,836 49,457 Regulatory Charges to be collected 67,260 0 Interest on Shareholders' Equity / Dividends payable 1,068,548 500,513 Labor obligations 36,212 45,094 Amounts Payable - Vivest 855 871 Special obligations - Reversal/Amortization 2,480 2,480 Others 56,930 43,751 2,361,322 1,372,497 NON-CURRENT Long-term Liabilities Loans and financing 1,182,886 1,208,301 Debentures 3,664,357 2,961,318 Leasing 42,856 44,742 Benefit to employess - Actuarial Deficit 394,078 381,978 Deferred PIS and COFINS 1,527,911 1,318,796 Deferred Income Tax and Social Contribution 3,439,088 2,955,826 Regulatory Charges to be collected 50,331 48,065 Provisions 128,730 88,682 Global Reversal Reserve - RGR 13,512 14,132 Others 36,621 77,624 Total long-term liabilities 10,480,370 9,099,464 NET EQUITY Shareholders' Equity 3,590,020 3,590,020 Capital Reserves 666 666 Profits Reserve 9,332,529 9,863,692 Actuarial Surplus -364,659 -364,659 Other comprehensive results 166,601 140,114 Accumulated Profits / Losses 582,624 114,129 Additional proposed dividends 0 524,450 13,307,781 13,868,412

Non-controlling shareholders' share of investment funds 355,926 371,159

13,663,707 14,125,442 40

Total Liabilities and Shareholders' Equity 26,505,399 24,592,358

Attachment IX – Income Statement – IFRS

Income Statement Consolidated (BRL thousand) 1Q21 1Q20 Chg (%) Gross Operational Revenue 1,260,391 979,128 30.86% Infrastructure Revenue 256,567 193,571 32.54% O&M Gross Revenue 318,120 297,169 7.05% Efficiency Gain in Infrastructure Implementation 20,922 0 N.A. Remuneration of concession assets 679,010 480,688 41.26% Other Revenues 6,694 7,700 -13.06% Deductions from Operational Revenue -172,373 -127,001 35.73% Net Operational Revenue 1,088,018 852,127 30.14% Operational Costs and Expenses -325,176 -268,335 21.18% Personnel -95,897 -77,351 23.98% Materials -71,440 -103,860 -31.22% Services -127,786 -63,413 101.51% Depreciation -5,119 -4,468 14.57% Others -24,934 -19,243 29.57% Service Income 762,842 583,792 34.25% Financial Income -115,769 -49,311 134.77% Income from Financial Investments 9,761 21,983 -55.60% Result of Liquid Monetary Variation -68,131 -26,159 160.45% Interest costs 908 -418 -317.22% Interest/Charges on loans -63,097 -37,261 69.34% Others 4790 -7,456 -164.24% Operational Result 647,073 534,481 24.98% Equity Income 124,176 132,992 -6.63% Other Operating Revenues/Expenses -10,686 4662 -329.21% Earnings Before Taxes 760,563 672,135 13.16%

Income tax and Social Contribution on Earnings -176,084 -150,055 17.35%

Current -210,719 -77,594 171.57% Deferred 34,635 -72,461 -147.80% Consolidated Profit/Loss for the Period before 584,479 522,080 11.95% Non-Controlling Shareholder's Stake Non-Controlling Shareholder's Stake -1,855 -15,497 -88.03% Consolidated Profit/Loss for the Period 582,624 506,583 15.01%

Attachment X – Cash Flow under IFRS (BRL thousand)

Cash Flow from Operations Consolidado

(BRL thousand) 03/31/2021 12/31/2020 Cash flow from operational activities 1,346,089 3,725,053 Net earnings 584,479 3,382,650 Employee benefit - actuarial deficit 12,100 15,368 Deferred PIS and COFINS 211,189 131,399 Depreciation and amortization 5,119 19,791 Deferred income taxes and social contribution 553,005 419,462 Lawsuit Liabilities -1,847 34,793 Residual cost of imobilized/intangible asset 3 659 Tax benefit - incorporated goodwill 9 37 Realization of concession assets in the acquisition of subsidiary 623 2,491 Realization of the loss in jointly controlled -1,187 -7,900 Result of equity income -124,176 -472,525 Income from financial investments -655 -4,437 Interest and exchange variations on loans, financing and debentures 94,249 0 Interest and monetary and exchange variations on assets and liabilities 13,178 203,265 Asset Variations (2,392,804) (2,515,276) Restricted cash 4,589 -156 Concession asset -2,276,454 -2,253,894 Inventories -7,057 61,529 Accounts Receivable from the State Finance Secretariat -42,504 -202,667 Recoverable taxes and contributions -43,388 3,528 Prepaid expenses -30,195 -1,723 Pledges and Escrows -2,861 9,856 Credit with subsidiaries 223 -14,292 Others 4,843 -117,457 Liabilities Variations (51,029) 152,327 Suppliers -52,975 -14,428 Taxes and social charges to be collected 13,131 163,522 Labor obligations -8,882 11,753 Regulatory charges to be collected -2,583 6,662 Provisions -4,742 -14,925 Amounts Payable - Vivest -16 -1,302

Obligations linked to the concession of the service -620 -2,480

Global Reversion Reserve 0 0 Others 5,658 3,525 Net Cash from Operating Activities - 1,362,104 Investments Activites Cash Flow (612,750) (177,309) Financial investments -265,886 -1,744,485 Redemptions of financial investments 235,132 1,767,685 Imobilized -1,446 -7,525 Intangible -561,550 -5,511 Investments -19,000 -207,166 Received dividends 0 19,693 Cash used in financing activities 496,845 286,571 Addition to loans and debentures 1,046,037 2,255,516 Loan payments (principal) -31,807 -1,263,352 Loan payments (interest) -35,977 -167,144 Leasing Payments (principal and interest) -3,042 -13,275 Leasing Payments (interest) 0 0 Transactions with non-controlling shareholders -1,855 -21,147 Derivative instruments 11,067 243,342 Paid dividends and interest on equity -487,578 -747,369 Net variation in Cash and Cash Equivalents (1,213,649) 1,471,366 Opening Balance of Cash and Cash Equivalents 853,688 595,971 Closing Balance of Cashand Cash Equivalents 2,067,337 2,067,337 Cash and cash equivalents -1,213,649 1,471,366

Attachment XI – EBITDA IFRS vs. Regulatory (BRL thousand) Consolidated 1Q21 1Q20 Chg (%) EBITDA IFRS (ICVM 527) 882.08 609 44.7% (-) Infrastructure implementation revenue -235.6 -146.6 60.7% (-) Concession assets remuneration -679.0 -478.9 41.8% (-) Efficiency gains in infrastructure implementation -20.9 0.0 N.A. (-) O&M Revenue -318.1 -297.2 7.1% (+) Electric network use revenue 991.0 843.8 17.5% (+) Deferred PIS and COFINS 25.0 7.8 221.3% (+) Infrastructure implementation cost 185.7 141.1 31.7% (-) O&M Cost -1.2 -4.3 -71.3% (-) General and Administrative expenses -4.8 -0.5 782.9% (-) Equity Income -123.0 -42.2 191.4% (-) Other operational revenues (expenses) -3.1 -14.9 -79.4% REGULATORY EBITDA (ICVM 527) 698.1 617 13.1% Equity Income -1.2 -20.3 -94.1% Receipt of retroactive PA (RTP and RBSE) 72.6 0.0 N.A. Non-recurring costs and expenses¹ 1.0 2.5 -60.0% ADJUSTED EBITDA 770.5 600 28.5%

¹Growth projects, COVID-19-related expenses and donations, lawyers’ fees, notice of violation and others.