UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER
PURSUANT TO RULE 13a-16 OR 15d-16
UNDER THE SECURITIES EXCHANGE ACT OF 1934
For the month of May 2024
Commission File Number 001-36487

Atlantica Sustainable Infrastructure plc
(Exact name of Registrant as specified in its charter)

Not applicable
(Translation of Registrant’s name into English)

Great West House, GW1, 17th floor
Great West Road
Brentford, TW8 9DF
United Kingdom
Tel: +44 203 499 0465

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

☒ Form 20-F |  | ☐ Form 40-F

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): ☐
Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): ☐

May 8, 2024 Q1 2024 Earnings Presentation

DISCLAIMER Forward Looking Statements This presentation contains forward-looking statements. These forward-looking statements include, but are not limited to, all statements other than statements of historical facts contained in this presentation, including, without limitation, those regarding our future financial position and results of operations, our strategy, plans, objectives, goals and targets, future developments in the markets in which we operate or are seeking to operate. In some cases, you can identify forward-looking statements by terminology such as "anticipate“, "believe," "could“, "estimate“, "expect“, "guidance“, "may“, "plan“, "should" or "will" or the negative of such terms or other similar expressions or terminology. By their nature, forward-looking statements involve risks and uncertainties because they relate to events and depend on circumstances that may or may not occur in the future. Forward-looking statements speak only as of the date of this presentation and are not guarantees of future performance and are based on numerous assumptions. Our actual results of operations, financial condition and the development of events may differ materially from (and be more negative than) those made in, or suggested by, the forward-looking statements. Except as required by law, we do not undertake any obligation to update any forward-looking statements to reflect events or circumstances after the date hereof or to reflect anticipated or unanticipated events or circumstances. Investors should read the section entitled "Item 3.D.—Risk Factors" and the description of our segments and business sectors in the section entitled "Item 4.B. Information on the Company—Business Overview", each in our Annual Report on Form 20-F for the fiscal year ended December 31, 2023, filed with the Securities and Exchange Commission (“SEC”), for a more complete discussion of the risks and factors that could affect us. Forward-looking statements include, but are not limited to, statements relating to: our anticipated exposure to current market risks, including the potential impact from foreign exchange rates and interest rates on cash available for distribution (“CAFD”); equity investments; CAFD estimates, including per currency, geography and sector; net corporate leverage based on CAFD estimates; debt refinancing; the performance of our long-term contracts; self-amortizing project debt structure and debt reduction; return from the recently acquired UK wind assets, sale of electricity under PPAs, investments in assets to be built and their respective ready to build (“Rtb”) and commercial operation dates; proceeds expected from the sale of our equity interest in Monterrey; the use of non-GAAP measures as a useful tool for investors including enterprise value to EBITDA multiple; dividends; and various other factors, including those factors discussed under “Item 3.D.—Risk Factors” and “Item 5.A.—Operating Results” in our Annual Report on Form 20-F for the fiscal year ended December 31, 2023 filed with the SEC. The CAFD guidance used in this presentation was estimated as of May 8, 2024. This estimate is based on assumptions believed to be reasonable as of the date Atlantica Sustainable Infrastructure plc (“Atlantica”, the “Company”, “we” or “us”) published its 2023 Financial Results. We disclaim any current intention to update such guidance, except as required by law. Non-GAAP Financial Measures This presentation also includes certain non-GAAP financial measures, including Adjusted EBITDA, CAFD, CAFD per share and enterprise value to EBITDA. Non-GAAP financial measures are not measurements of our performance or liquidity under IFRS as issued by IASB and should not be considered alternatives to operating profit or profit for the period or net cash provided by operating activities or any other performance measures derived in accordance with IFRS as issued by the IASB or any other generally accepted accounting principles or as alternatives to cash flow from operating, investing or financing activities. Please refer to the appendix of this presentation for a reconciliation of the non-GAAP financial measures included in this presentation to the most directly comparable financial measures prepared in accordance with IFRS as well as the reasons why management believes the use of non-GAAP financial measures (including CAFD, CAFD per share, Adjusted EBITDA and enterprise value to EBITDA) in this presentation provides useful information to investors. In our discussion of operating results, we have included foreign exchange impacts in our revenue and Adjusted EBITDA growth. The constant currency presentation is not a measure recognized under IFRS and excludes the impact of fluctuations in foreign currency exchange rates. We believe that constant currency information provides valuable supplemental information regarding our results of operations. We calculate constant currency amounts by converting our current period local currency revenue and Adjusted EBITDA using the prior period foreign currency average exchange rates and comparing these adjusted amounts to our prior period reported results. This calculation may differ from similarly titled measures used by others and, accordingly, the constant currency presentation is not meant to be a substitute for recorded amounts presented in conformity with IFRS as issued by the IASB nor should such amounts be considered in isolation.

Key Messages Stable revenue at $242.9 million in Q1 2024 compared with $242.5 million in Q1 2023 Excluding the estimated impact of $8.5 million in the first quarter of 2024 of the unscheduled outage at Kaxu that started in 2023, and net of insurance income related to this event. The plant restarted operations in mid-February 2024. EV (“Entreprise Value”) is defined as Atlantica´s expected investment. EBITDA is calculated as the average Net Income for the for the years 2023 and 2022 after adding back depreciation, amortization and impairment charges, income taxes, and interest expenses. See Reconciliation on page 26. Adjusted EBITDA 0.9%1 year-over-year decrease excluding the effect of the unscheduled outage at Kaxu Operating Cash Flow 57.3% year-over-year increase up to $65.6 million Signed a 15-year PPA for a 100 MW solar + storage project in California Closed the acquisition of two wind assets in operation in the UK at 6.6x EV / EBITDA2 multiple

HIGHLIGHTS Operating Results CAFD per share is calculated by dividing CAFD for the period by the weighted average number of shares for the period (see reconciliation on page 25). Excluding the estimated impact of $8.5 million in the first quarter of 2024 of the unscheduled outage at Kaxu that started in 2023, and net of insurance income related to this event. The plant restarted operations in mid-February 2024. Excluding $4.1 million from the sale of part of our equity interest in our development company in Colombia to a partner in Q1 2023. US$ in million (except CAFD per share) 2024 2023 ∆ Reported Excluding Kaxu impact2 & Q1-2023 CAFD One-off3 Revenue 242.9 242.5 0.2% Adjusted EBITDA 164.2 174.2 (5.7)% (0.9)%2 CAFD 50.9 61.0 (17)% (11)%3 CAFD per share1 0.44 0.53 (17)% (11)%3 First 3 Months

HIGHLIGHTS Performance by Region and Sector North America South America EMEA Renewables Efficient Nat. Gas & Heat Transmission Lines Water Revenue Adjusted EBITDA US$ in million Revenue Adjusted EBITDA By Region By Sector Q1 2024 Q1 2023 ∆ 86.2 72.8 18% 55.0 52.0 6% Q1 2024 Q1 2023 ∆ 44.7 43.7 2% 34.6 33.8 2% Q1 2024 Q1 2023 ∆ 112.0 126.0 (11)% 74.6 88.4 (16)% Q1 2024 Q1 2023 ∆ 162.2 172.6 (6)% 107.2 119.1 (10)% Q1 2024 Q1 2023 ∆ 36.0 27.4 31% 23.3 22.6 3% Q1 2024 Q1 2023 ∆ 30.5 28.8 6% 24.8 23.5 6% Q1 2024 Q1 2023 ∆ 14.2 13.7 4% 8.9 9.0 (1)%

Includes 49% of Vento II production since its acquisition. Includes curtailment in wind assets for which we receive compensation. Represents total installed capacity in assets owned or consolidated at the end of the period, regardless of our percentage of ownership in each of the assets, except for Vento II, for which we have included our 49% interest. GWh produced includes 30% share of the production from Monterrey. Availability refers to the time during which the asset was available to our client totally or partially divided by contracted or budgeted availability, as applicable. Includes 43 MW corresponding to our 30% share in Monterrey and 55 MWt corresponding to thermal capacity from Calgary District Heating. KEY OPERATIONAL METRICS Steady Operational Performance Renewables Q1 2024 Q1 2023 GWh produced1 1,063 1,192 MW in operation2 2,203 2,161 Transmission Lines Q1 2024 Q1 2023 Availability4 100.0% 100.0% Miles in operation 1,229 1,229 Efficient Natural Gas & Heat Water Q1 2024 Q1 2023 Availability4 102.3% 100.8% Mft3 in operation2 17.5 17.5 Q1 2024 Q1 2023 GWh produced3 636 600 Availability4 102.3% 94.9% MW in operation5 398 398

Consolidated cash as of March 31, 2024, increased by $3.8 million vs December 31, 2023, including FX translation differences of $(3.8) million. CASH FLOW Operating Cash Flow US$ in million 2024 2023 Adjusted EBITDA 164.2 XX 174.2 Share in Adjusted EBITDA of unconsolidated affiliates (12.5) (11.8) Net interest and income tax paid (26.7) (30.2) Changes in working capital (41.1) ) (93.3) Non-monetary adjustments and other (18.3) 2.8 OPERATING CASH FLOW 65.6 41.7 Acquisitions of subsidiaries and entities under the equity method and investments in assets under development and construction (84.4) (9.5) Investments in operating concessional assets (2.4) (7.6) Distributions from entities under the equity method & other 16.1 18.0 INVESTING CASH FLOW (70.7) 0.9 FINANCING CASH FLOW 12.7 (42.1) Net change in consolidated cash1 7.6 0.4 First Quarter

GROWTH UPDATE Progress in Development & Construction Complemented by M&A 100 MW storage for four hours. The assets are regulated until 2033 and 2027, under the UKs green attribute regulations (“ROCs”). The assets also receive Renewable Energy Guarantees of Origin (“REGOs”) until the end of their useful life. EV (“Enterprise Value”) is defined as Atlantica’s investment in these two assets. EBITDA is calculated as the average Net Income for the for the years 2023 and 2022 after adding back depreciation, amortization and impairment charges, income taxes, and interest expenses. See Reconciliation on page [26]. Expected proceeds of approximately $43 million subject to final transaction costs, taxes and ongoing discussions with our partner. There is an earn-out mechanism that could result in additional proceeds for Atlantica of up to approximately $7 million between 2026 and 2028 100 MW PV + storage1 project, with RTB expected in 2024 15-Year PPA with an investment grade offtaker New PPA in California Acquisition of 2 Wind Assets in the UK 32 MW wind representing a $66 million investment Regulated revenue2 and no project debt 6.6x EV/EBITDA3 Return expected to be enhanced by use of existing NOLs carryforwards in the UK Other Projects Signed PPA for Chile PV 3 including the battery storage expansion under construction (142 MWh) Advanced negotiations for a PPA for a 27.5 MWDC / 22 MWAC PV project in Spain Closed sale of Monterrey4

Appendix

Based on CAFD estimates for the 2024-2027 period as of May 8, 2024, for the assets as of December 31, 2023, including assets that have reached COD before May 8, 2024. See “Disclaimer – Forward Looking Statements”. Euro denominated cash flows from assets in Europe, net of euro-denominated corporate interest payments and general and administrative expenses, are hedged through currency options on a rolling basis 100% for the next 12 months and 75% for the following 12 months. Based on weighted outstanding debt as of March 31, 2024. Calculated as weighted average years remaining as of March 31, 2024, based on CAFD estimates for the 2024-2027 period, including assets that have reached COD before May 8, 2024. See “Disclaimer – Forward Looking Statements”. Calculated as a % of Revenue from FY 2023. Revenues non-dependent on natural resources includes transmission lines, efficient natural gas and heat, water assets and approximately 76% revenues received by our Spanish assets. SIZEABLE AND DIVERSIFIED ASSET PORTFOLIO Portfolio Breakdown Based on Estimated CAFD1 Geography1 Interest rates Currency Highly Sector1 69% Renewable 14% Eff. Natural Gas & Heat 13% Transmission Lines 4% Water of interest rates in project debt are fixed or hedged3 ~92 % Denominated in USD or hedged1,2 % > Contracted years Weighted Average PPA Life Remaining4 50 of Revenue non dependent on natural resource5 % (~100%)6 Stable Cashflows > 38% North America 35% Europe 20% South America 7% RoW 13 90

Net corporate debt is calculated as long-term corporate debt plus short-term corporate debt minus cash and cash equivalents at Atlantica’s corporate level. Net corporate leverage is calculated as net corporate debt divided by midpoint 2024 CAFD guidance before corporate debt service. CAFD before corporate debt service is calculated as CAFD plus corporate debt interest paid by Atlantica. Net project debt is calculated as long-term project debt plus short-term project debt minus cash and cash equivalents at the consolidated project level. NET DEBT Net Corporate Debt to CAFD pre corporate interest at 3.8x Corporate Mar. 31, 2024 Dec. 31, 2023 1,126.8 1,051.7 3,895.9 3,904.0 Project Net Project Debt3 3.8x 3.8x Net Corporate Debt1 Net Corporate Debt/ CAFD pre corporate debt service2 US$ in million

HISTORICAL FINANCIAL REVIEW Key Financials by Quarter (1/2) “Deposits into/ withdrawals from restricted accounts” and “Change in non-restricted cash at project level” are calculated on a constant currency basis to reflect actual cash movements isolated from the impact of variations generated by foreign exchange changes during the period. Prior periods have been recalculated to conform to this presentation. Dividends are paid to shareholders in the quarter after they are declared. (3) Number of shares outstanding on the record date corresponding to each dividend, except the shares issued under the ATM program between the dividend declaration date and the dividend record date, as applicable. (4) Excludes decreases in project cash allocated to investments in assets under development and construction. 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 Revenue 247,452 307,832 303,121 243,624 1,102,029 242,509 312,110 303,964 241,311 1,099,894 242,933 Adjusted EBITDA 173,626 228,678 228,336 166,459 797,100 174,204 229,624 223,454 167,640 794,922 164,219 Atlantica’s pro-rata share of EBITDA from unconsolidated affiliates (14,202) (15,988) (7,387) (8,192) (45,769) (11,796) (7,755) (5,726) (9,370) (34,647) (12,514) Non-monetary items 10,413 10,940 10,839 (4,196) 27,996 649 (2,384) 9,973 (11,357) (3,119) (17,984) Accounting provision for electricity market prices in Spain 7,141 10,585 10,507 (2,980) 25,253 (1,153) (4,460) 9,503 (7,385) (3,494) (13,098) Difference between billings and revenue in assets accounted for as concessional financial assets 18,169 15,050 14,978 13,434 61,630 16,441 16,695 15,099 10,657 58,892 9,662 Income from cash grants in the US (14,897) (14,695) (14,645) (14,650) (58,888) (14,639) (14,619) (14,629) (14,629) (58,516) (14,548) Maintenance Capex (2,844) (3,614) (7,283) (4,847) (18,588) (7,630) (12,041) (5,067) (3,191) (27,929) (2,391) Dividends from unconsolidated affiliates 31,870 11,921 12,411 11,493 67,695 12,401 3,063 13,416 5,449 34,329 14,922 Net interest and income tax paid (16,546) (112,705) (32,885) (115,148) (277,284) (30,179) (108,666) (21,059) (112,805) (272,708) (26,738) Changes in other assets and liabilities (5,588) 6,415 52,186 49,885 102,896 (92,980) (8,295) (11,516) 20,054 (92,738) (39,371) Deposits into/withdrawals from restricted accounts1 11,805 8,020 (20,503) 33,696 33,018 9,820 11,418 (8,813) 35,192 47,617 (7,424) Change in non-restricted cash at project companies1,4 (103,116) 51,501 (135,718) 125,662 (61,672) 43,114 73,659 (98,297) 107,848 126,325 8,639 Dividends paid to non-controlling interests (6,221) (9,800) (10,421) (12,767) (39,209) (6,011) (11,180) (8,568) (5,674) (31,433) (5,558) Principal amortization of indebtedness net of new indebtedness at projects (24,789) (112,427) (27,912) (183,183) (348,311) (30,543) (103,918) (28,208) (142,211) (304,880) (24,879) Cash Available For Distribution (CAFD) 54,407 62,941 61,662 58,862 237,872 61,049 63,525 59,589 51,577 235,740 50,921 Dividends declared2 50,202 51,332 51,645 51,645 204,824 51,688 51,688 51,691 51,691 206,758 51,691 # of shares3 114,095,845 115,352,085 116,055,126 116,055,126 116,153,273 116,153,273 116,159,054 116,159,054 116,159,054 DPS (in $ per share) 0.44 0.445 0.445 0.445 1.775 0.445 0.445 0.445 0.445 1.780 0.445 Key Financials US$ in thousands

Debt Details 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 Project Debt 5,037.0 4,735.5 4,621.9 4,553.1 4,553.1 4,596.6 4,438.2 4,412.1 4,319.3 4,319.3 4,301.1 Project Cash (625.9) (545.1) (675.8) (540.2) (540.2) (493.5) (414.0) (546.6) (415.3) (415.3) (405.2) Net Project Debt 4,411.1 4,190.4 3,946.1 4,012.9 4,012.9 4,103.1 4,024.2 3,865.5 3,904.0 3,904.0 3,895.9 Corporate Debt 1,056.1 1,000.1 955.5 1,017.2 1,017.2 1,077.4 1,051.2 1,046.6 1,084.7 1,084.7 1,173.7 Corporate Cash (113.1) (123.1) (105.8) (60.8) (60.8) (109.4) (72.8) (48.0) (33.0) (33.0) (46.9) Net Corporate Debt 943.0 877.0 849.7 956.4 956.4 968.0 978.4 998.6 1,051.7 1,051.7 1,126.8 Total Net Debt 5,354.1 5,067.4 4,795.8 4,969.3 4,969.3 5,071.1 5,002.6 4,864.1 4,955.7 4,955.7 5,022.7 Net Corporate Debt / CAFD pre corporate interests1 3.3x 3.1x 3.0x 3.4x 3.4x 3.3x 3.4x 3.4x 3.8x 3.8x 3.8x HISTORICAL FINANCIAL REVIEW Key Financials by Quarter (2/2) US$ in million (1) Ratios presented are the ratios shown on each earnings presentation relating to such period.

HISTORICAL FINANCIAL REVIEW Segment Financials by Quarter 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 by Geography NORTH AMERICA 74,304 124,968 124,423 81,352 405,047 72,840 129,331 136,574 86,143 424,888 86,232 SOUTH AMERICA 38,528 39,804 44,217 43,892 166,441 43,720 47,793 48,756 47,858 188,127 44,678 EMEA 134,620 143,060 134,481 118,380 530,541 125,949 134,986 118,634 107,310 486,879 112,023 by Business Sector RENEWABLES 182,101 238,234 232,423 168,619 821,377 172,601 238,610 228,907 162,639 802,756 162,211 EFFICIENT NAT. GAS & HEAT 25,327 28,091 28,526 31,647 113,591 27,403 27,407 30,164 33,443 118,417 35,970 TRANSMISSION LINES 26,620 28,234 28,425 29,994 113,273 28,831 32,167 30,827 31,651 123,476 30,486 WATER 13,404 13,273 13,747 13,364 53,788 13,674 13,927 14,066 13,579 55,245 14,266 Total Revenue 247,452 307,832 303,121 243,624 1,102,029 242,509 312,110 303,964 241,311 1,099,894 242,933 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 by Geography NORTH AMERICA 58,266 102,913 96,981 51,828 309,988 51,969 102,069 106,646 58,580 319,264 55,026 SOUTH AMERICA 29,129 29,715 36,236 31,471 126,551 33,788 40,640 37,621 34,673 146,722 34,568 EMEA 86,231 96,051 95,118 83,161 360,561 88,447 86,915 79,186 74,388 328,936 74,625 by Business Sector RENEWABLES 122,223 174,606 173,022 118,165 588,016 119,122 173,448 167,872 115,262 575,704 107,250 EFFICIENT NAT. GAS & HEAT 21,699 22,315 22,794 17,752 84,560 22,610 21,396 22,520 20,867 87,393 23,287 TRANSMISSION LINES 20,523 22,656 23,047 21,784 88,010 23,470 25,780 24,006 22,787 96,043 24,827 WATER 9,181 9,102 9,473 8,758 36,514 9,002 9,000 9,055 8,725 35,782 8,855 Total Adjusted EBITDA 173,626 228,678 228,336 166,459 797,100 174,204 229,624 223,453 167,641 794,922 164,219 Adjusted EBITDA Revenue US $ in thousands

1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 RENEWABLES3 (GWh) 1,094 1,554 1,507 1,164 5,319 1,192 1,611 1,580 1,075 5,458 1,063 (GWh)4 625 626 647 603 2,501 600 630 662 657 2,549 636 (availability %)5 100.3% 99.9% 101.1% 95.1% 98.9% 94.9% 99.2% 102.3% 102.1% 99.6% 102.3% TRANSMISSION LINES (availability %)5 99.9% 99.9% 100.0% 100.0% 100.0% 100.0% 100.0% 99.9% 99.9% 100.0% 100.0% WATER (availability %)5 104.5% 99.9% 103.3% 101.4% 102.3% 100.8% 100.1% 102.5% 95.2% 99.7% 102.3% 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 RENEWABLES1 (MW) 2,044 2,048 2,121 2,121 2,121 2,161 2,161 2,161 2,171 2,171 2,203 EFFICIENT NAT. GAS & HEAT2 (MW) 398 398 398 398 398 398 398 398 398 398 398 TRANSMISSION LINES (Miles) 1,229 1,229 1,229 1,229 1,229 1,229 1,229 1,229 1,229 1,229 1,229 WATER1 (Mft3/day) 17.5 17.5 17.5 17.5 17.5 17.5 17.5 17.5 17.5 17.5 17.5 Capacity in operation (at the end of the period) Production / Availability Represents total installed capacity in assets owned or consolidated at the end of the period, regardless of our percentage of ownership in each of the assets, except for Vento II, for which we have included our 49% interest. Includes 43 MW corresponding to our 30% share in Monterrey and 55 MWt corresponding to thermal capacity from Calgary District Heating since May 14, 2021. Includes 49% of Vento II production since its acquisition. Includes curtailment in wind assets for which we receive compensation. GWh produced includes 30% share of the production from Monterrey. Availability refers to the time during which the asset was available to our client totally or partially divided by contracted or budgeted availability, as applicable. EFFICIENT NAT. GAS & HEAT HISTORICAL FINANCIAL REVIEW Key Performance Indicators

Capacity factor ratio represents actual electrical energy output over a given period of time divided by the maximum possible electrical energy output assuming continuous operation at full nameplate capacity over that period. Historical Capacity Factors are calculated from the date of entry into operation or the acquisition of each asset. Some capacity factors are not indicative of a full period of operations. Includes Chile PV 3 since Q3 2022. Includes curtailment production in wind assets for which we receive compensation. Scheduled major overhaul carried out by Siemens, the original equipment manufacturer, which lasted 28 days longer than expected and a subsequent unscheduled outage. HISTORICAL FINANCIAL REVIEW Capacity Factors Historical Capacity Factors1 1Q22 2Q22 3Q22 4Q22 2022 1Q23 2Q23 3Q23 4Q23 2023 1Q24 SOLAR US 17.2% 39.1% 32.4% 16.6% 26.3% 15.2% 42.4% 36.9% 18.5% 28.3% 17.5% Chile2 25.3% 20.4% 24.6% 28.8% 24.8% 27.6% 21.4% 19.0% 18.5% 21.6% 22.2% Spain 7.3% 23.6% 27.9% 5.8% 16.2% 11.7% 26.9% 30.1% 7.2% 19.0% 6.7% Italy 12.7% 19.7% 20.0% 9.2% 15.4% 11.8% 16.9% 18.3% 8.3% 13.8% 10.5% Kaxu 36.9% 27.2% 28.8% 44.6% 34.4% 45.2% 21.2% 4.9%4 0.0%4 17.7% 12.9%4 Colombia 27.1% 24.0% 24.7% 23.4% 24.8% 20.6% 22.8% 27.3% 24.0% 21.7% 26.9% US 38.1% 35.6% 20.3% 34.8% 32.2% 37.7% 26.4% 20.2% 31.9% 29.0% 36.4% Uruguay3 34.5% 27.7% 38.2% 41.8% 35.6% 33.6% 29.4% 42.3% 46.3% 37.9% 35.4% WIND

Exchange rates as of March 31, 2024 (EUR/USD = 1.0790) and December 31, 2023 (EUR/USD = 1.1039). Restricted cash is cash which is restricted generally due to requirements of certain project finance agreements. US $ in million1 As of Mar. 31 2024 As of Dec. 31 2023 Corporate cash at Atlantica 46.9 33.0 Existing available revolver capacity 305.0 378.1 Total Corporate Liquidity 351.9 411.1 Cash at project companies 405.2 415.3 - Restricted2 184.8 177.0 - Other 220.4 238.3 LIQUIDITY Liquidity Position

Does not include assets without PPAs or partially contracted. Calculated as weighted average years remaining as of March 31, 2024 based on CAFD estimates for the 2024-2027 period, including assets that have reached COD before May 8, 2024. See “Disclaimer – Forward Looking Statements”. (3) Regulation term in the case of Spain and Chile TL3. (4) From the total amount of $211 million project debt, $74 million are progressively repaid following a theoretical 2036 maturity, with a legal maturity in 2027. The remaining $137 million are expected to be refinanced in or before 2027. 4 Refinancing opportunities could increase CAFD in earlier years Tails in most assets after debt amortization PPAs with predefined prices for ~13 years on average2 Possibility to extend life in many assets (excluding ATN and ATS) Weighted Average Life Project debt term Contract term3 LONG TERM STABLE CASH FLOW Portfolio of Contracted Assets1

Exchange rates as of March 31, 2024 (EUR/USD =1.0790). Amounts include principal amounts outstanding, unless stated otherwise. As of March 31, 2024, $305.0 million was available under the Revolving Credit Facility. The latter has a total limit of $450 million. US $ in million1 Maturity Amounts2 Credit Facilities (Revolving Credit Facility)3 2025 145.3 (Other facilities)4 2024 – 2028 54.6 Green Exchangeable Notes5 2025 111.7 2020 Green Private Placement6 (€ denominated) 2026 311.7 Note Issuance Facility 20207 (€ denominated) 2027 149.1 Green Senior Notes8 2028 401.3 Total 1,173.7 Other facilities include the Commercial Paper Program, accrued interest payable and other debt. Senior unsecured notes dated July 17, 2020, exchangeable into ordinary shares of Atlantica, cash, or a combination of both, at Atlantica’s election. Senior secured notes dated April 1, 2020, of €290 million. Senior unsecured note facility dated July 8, 2020, of €140 million. Green Senior Unsecured Notes dated May 18, 2021, of $400 million. CORPORATE DEBT DETAILS Corporate Debt as of March 31, 20241

fixed or hedged1 Project Debt Calculated as the weighted average of the % of fixed or hedged corporate debt and the % of fixed or hedged project debt based on outstanding balance as of March 31, 2024. (2) See our Annual Report on Form 20-F for the fiscal year ended December 31, 2023 for additional information on the specific interest rates and hedges. INTEREST RATE RISK COVERAGE 91%1 of Consolidated Debt Fixed or Hedged2 (3) Percentage fixed or hedged. (4) Weighted average based on outstanding balance as of March 31, 2024. (5) Other facilities include the Commercial Paper Program, accrued interest payable and other debt. (6) Hedged at 100% until the end of 2024. INSTRUMENT INTEREST TYPE MARCH 31, 2024 Revolving Credit Facility (RCF) Variable 144.5 Green Exchangeable Notes Fixed 110.8 2020 Green Private Placement Fixed 311.6 Note Issuance Facility 2020 Hedged (100%)6 149.1 Green Senior Notes Fixed 396.2 Other facilities5 Fixed 61.5 Total Outstanding Debt 1,173.7 Hedged4 12.7% Fixed4 75.0% Total Fixed or Hedged 87.7% Corporate Debt of Corporate Debt ~88% of Project Debt & ~92% ASSET INTEREST TYPE FIXED1,3 Solana fixed 100% Mojave fixed 100% Coso hedged 100% Solaben 2 hedged 90% Solaben 3 hedged 90% Logrosan hedged 100% Solacor 1 hedged 90% Solacor 2 hedged 90% Helioenergy 1 hedged 99% Helioenergy 2 hedged 99% Solnova 1 hedged 90% Solnova 3 hedged 90% Solnova 4 hedged 90% Helios 1/2 fixed 100% Solaben 1/6 fixed 100% Palmatir fixed 94% Cadonal hedged 88% Melowind hedged 75% ACT hedged 75% ATN fixed 100% ATN 2 fixed 100% ATS fixed 100% Quadra 1 hedged 75% Quadra 2 hedged 75% Palmucho hedged 75% Skikda fixed 100% Tenes fixed 100% Kaxu hedged 43% Chile PV 1&2 hedged 80% Rioglass hedged 78% Montesejo fixed 100% Hedged4 41.5% Fixed4 50.0% Total Fixed or Hedged 91.5%

Asset ($ Millions) Full Year Forescasted ammortization Schedule on non-recourse Project debt as of September 30, 2023 ($ millions) 2024 2025 2026 2027 2028 Thereafter Total Solana 25.4 26.8 29.5 32.4 35.4 418.6 568.1 Mojave 37.6 38.1 39.4 40.7 36.2 279.2 471.2 Kaxu 26.3 26.0 29.3 31.9 34.7 85.8 234 Helios 1/2 22.2 22.4 21.8 22.2 22.5 168.6 279.7 Solaben 1/6 14.3 15.2 15.9 16.3 17.0 101.0 179.7 Solaben 2/3 13.2 19.4 21.5 23.1 115.94 128.1 321.2 Solnova 1/3/4 31.5 31.5 33.1 32.9 31.7 177.4 338.1 Helioenergy 1/2 19.3 20.5 19.4 20.7 23.0 132.3 235.2 Solacor 1/2 14.7 15.1 15.5 15.9 16.1 132.3 209.6 Chile PV 1 2.6 1.0 1.1 1.6 2.2 41.7 50.2 Chile PV 2 1.3 1.4 2.4 2.0 2.2 11.5 20.8 Italy PV 1, 3 & 4 0.6 0.6 0.3 - - - 1.5 Total Solar 209.0 218.0 229.2 239.7 336.9 1,676.5 2,909.3 Palmatir 7.0 6.6 7.0 7.5 8.0 30.2 66.3 Cadonal 3.5 3.1 3.4 3.6 3.9 26.8 44.3 Melowind 4.8 5.0 5.1 4.8 5.7 40.8 66.2 Total Wind 15.3 14.7 15.5 15.9 17.6 97.8 176.8 ATN 6.1 6.4 6.9 7.3 6.7 48.2 81.6 ATS 12.0 8.3 9.5 10.7 12.1 332.0 384.6 ATN 2 5.0 5.1 5.4 5.4 5.6 14.2 40.7 Quadra 1/2 & Palmucho 5.5 6.1 6.6 7.3 8.0 20.7 54.2 Total Transmission 28.6 25.9 28.4 30.7 32.4 415.1 561.1 Skikda 2.6 - - - - - 2.6 Tenes 8.6 8.6 8.9 9.3 9.6 28.7 73.7 Total Water 11.2 8.6 8.9 9.3 9.6 28.7 76.3 Coso 14.6 14.2 14.7 145.15 - - 188.6 ACT 39.2 42.3 54.6 59.0 68.0 138.4 401.5 Rioglass CSP 2.4 1.6 1.2 0.3 0.1 - 5.6 Total Other 56.2 58.1 70.5 204.4 68.1 138.4 595.7 Total Non-Recourse Project Debt 320.3 325.3 352.5 500.0 464.6 2,356.5 4,319.3 No refinancing risk at the project level3 Includes $87.2 million tranche mini-perm structure to be refinanced in 2028. Includes $140 million tranche mini-perm structure to be refinanced in 2027. Project debt amortization schedule as of December 31, 2023. Not including unconsolidated affiliates. Only 5% of our project debt needs to be refinanced by 2027/2028, which corresponds to the two tranches in (4) and (5). PROJECT DEBT DETAILS Project Debt Amortization Schedule

Our management believes Adjusted EBITDA, CAFD, CAFD per share and enterprise value to EBITDA are useful to investors and other users of our financial statements in evaluating our operating performance because such measures provide investors with additional tools to compare business performance across companies and across periods. Adjusted EBITDA is widely used by investors to measure a company’s operating performance without regard to items such as interest expense, taxes, depreciation and amortization, which can vary substantially from company to company depending upon accounting methods and book value of assets, capital structure and the method by which assets were acquired. Our management believes CAFD and CAFD per share are relevant supplemental measure of the Company’s ability to earn and distribute cash returns to investors and is useful to investors in evaluating our operating performance because securities analysts and other interested parties use such calculations as a measure of our ability to make quarterly distributions. In addition, CAFD and CAFD per share are used by our management team for determining future acquisitions and managing our growth. Our management uses Adjusted EBITDA, CAFD and CAFD per share as measures of operating performance to assist in comparing performance from period to period and aims to use them on a consistent basis moving forward. They also readily view operating trends as a measure for planning and forecasting overall expectations, for evaluating actual results against such expectations, and for communicating with our board of directors, shareholders, creditors, analysts and investors concerning our financial performance. Adjusted EBITDA, CAFD and CAFD per share are widely used by other companies in the same industry. Our management believes enterprise value to EBITDA is a useful valuation tool widely used by investors when evaluating transactions as it compares the investment’s value to its earnings before interest, taxes depreciation and amortization. We present non-GAAP financial measures because we believe that they and other similar measures are widely used by certain investors, securities analysts and other interested parties as supplemental measures of performance and liquidity. The non-GAAP financial measures may not be comparable to other similarly titled measures employed by other companies and they may have limitations as analytical tools. These measures may not be fit for isolated consideration or as a substitute for analysis of our operating results as reported under IFRS as issued by the IASB. Non-GAAP financial measures and ratios are not measurements of our performance or liquidity under IFRS as issued by the IASB. Thus, they should not be considered as alternatives to operating profit, profit for the period, any other performance measures derived in accordance with IFRS as issued by the IASB, any other generally accepted accounting principles or as alternatives to cash flow from operating, investing or financing activities. Some of the limitations of these non-GAAP measures are: they do not reflect our cash expenditures, future requirements for capital expenditures or contractual commitments; they do not reflect changes in, or cash requirements for, our working capital needs; they may not reflect the significant interest expense, or the cash requirements necessary, to service interest or principal payments, on our debts; although depreciation and amortization are non-cash charges, the assets being depreciated and amortized will often need to be replaced in the future and Adjusted EBITDA, CAFD, CAFD per share and enterprise value to EBITDA do not reflect any cash requirements that would be required for such replacements; some of the exceptional items that we eliminate in calculating Adjusted EBITDA reflect cash payments that were made, or will be made in the future; and the fact that other companies in our industry may calculate Adjusted EBITDA, CAFD, CAFD per share and enterprise value to EBITDA differently than we do, which limits their usefulness as comparative measures. We define Adjusted EBITDA as profit/(loss) for the period attributable to the parent company, after previously adding back loss/(profit) attributable to non-controlling interest, income tax expense, financial expense (net), depreciation, amortization and impairment charges of entities included in our consolidated financial statements and depreciation and amortization, financial expense and income tax expense of unconsolidated affiliates (pro-rata of our equity ownership). CAFD is calculated as cash distributions received by the Company from its subsidiaries minus cash expenses of the Company, including debt service and general and administrative expenses, plus realized dispositions, gains and losses of ownership interest in assets. CAFD per share is calculated by dividing CAFD for the period by weighted average number of shares for the period. NON-GAAP FINANCIAL INFORMATION Reconciliation of Non-GAAP Measures

We define enterprise value to EBITDA as an investment’s enterprise value divide by its earnings before interest, taxes, depreciation and amortization. Information presented as the pro-rata share of our unconsolidated affiliates reflects our proportionate ownership of each asset in our property portfolio that we do not consolidate and has been calculated by multiplying our unconsolidated affiliates’ financial statement line items by our percentage ownership thereto. Note 7 to our consolidated financial statements as of and for the period ended March 31, 2024 includes a description of our unconsolidated affiliates and our pro rata share thereof. We do not control the unconsolidated affiliates. Multiplying our unconsolidated affiliates’ financial statement line items by our percentage ownership may not accurately represent the legal and economic implications of holding a noncontrolling interest in an unconsolidated affiliate. We include pro-rata share of depreciation and amortization, financial expense and income tax expense of unconsolidated affiliates because we believe it assists investors in estimating the effect of such items in the profit/(loss) of entities carried under the equity method (which is included in the calculation of our Adjusted EBITDA) based on our economic interest in such unconsolidated affiliates. Each unconsolidated affiliate may report a specific line item in its financial statements in a different manner. In addition, other companies in our industry may calculate their proportionate interest in unconsolidated affiliates differently than we do, limiting the usefulness of such information as a comparative measure. Because of these limitations, the information presented as the pro-rata share of our unconsolidated affiliates should not be considered in isolation or as a substitute for our or such unconsolidated affiliates’ financial statements as reported under applicable accounting principles. NON-GAAP FINANCIAL INFORMATION Reconciliation of Non-GAAP Measures

“Deposits into/ withdrawals from restricted accounts” and “Change in non-restricted cash at project level” are calculated on a constant currency basis to reflect actual cash movements isolated from the impact of variations generated by foreign exchange changes during the period. Excludes decreases in project cash allocated to investments in assets under development and construction. (in thousands of U.S. dollars) For the three-month period ended March 31 2024 2023 Loss for the period attributable to the Company (5,392) (10,990) Profit attributable to non-controlling interest 6 5,017 Income tax (22,620) (9,656) Depreciation and amortization, financial expense and income tax expense of unconsolidated affiliates (pro rata of our equity ownership) 5,563 5,609 Financial expense, net 79,626 80,434 Depreciation, amortization, and impairment charges 107,036 103,790 Adjusted EBITDA 164,219 174,204 Atlantica’s pro-rata share of EBITDA from unconsolidated affiliates (12,514) (11,796) Non-monetary items (17,984) 649 Accounting provision for electricity market prices in Spain (13,098) (1,153) Difference between billings and revenue in assets accounted for as concessional financial assets 9,662 16,441 Income from cash grants in the US (14,548) (14,639) Maintenance Capex (2,391) (7,630) Dividends from equity method investments 14,922 12,401 Net interest and income tax paid (26,738) (30,179) Changes in other assets and liabilities (39,371) (92,980) Deposits into/ withdrawals from restricted accounts1 (7,424) 9,820 Change in non-restricted cash at project level1,2 8,639 43,114 Dividends paid to non-controlling interests (5,558) (6,011) Debt principal repayments (24,879) (30,543) Cash Available For Distribution 50,921 61,049 RECONCILIATION Reconciliation of CAFD and Adjusted EBITDA to Profit for the period attributable to the Company

RECONCILIATION Reconciliation of Adjusted EBITDA to Net Cash Provided by Operating Activities (in thousands of U.S. dollars) For the three-month period ended March 31 For the three-month period ended June 30 2024 2023 Net cash provided by operating activities 65,583 41,706 Net interest and income tax paid 26,738 30,179 Changes in working capital 41,064 93,263 Non-monetary items & other 18,320 (2,740) Atlantica’s pro-rata share of EBITDA from unconsolidated affiliates 12,514 11,796 Adjusted EBITDA 164,219 174,204 Reconciliation of CAFD to CAFD per share For the three-month period ended March 31 2024 2023 CAFD (in thousands of U.S. dollars) 50,921 61,049 Weighted average number of shares (basic) for the period (in thousands) 116,159 116,140 CAFD per share (in U.S. dollars) 0.4384 0.5257

RECONCILIATION Reconciliation of EBITDA to Net Income for Acquisition of Wind Assets in United Kingdom (in thousands of U.S. dollars)2 Financial Year1 Average 2023 2022 2023 – 2022 Net Income 5,539 6,142 5,841 Income tax 1,748 1,483 1,615 Interest payable and other financial expenses 714 682 698 Depreciation and amortization 1,752 1,779 1,765 EBITDA 9,753 10,086 9,919 (in thousands of U.S. dollars)2 Total investment (100% ownership) 65,680 EV/EBITDA Multiple 6.6x Based on unaudited financial statements for financial years as historically reported from November to October of every twelve months. Transaction originally in GBP, assuming FX as of closing date (1.2601 GBP/USD).

As of May 8, 2024 ASSET TYPE STAKE LOCATION GROSSCAPACITY OFFTAKER RATING1 YEARS INCONTRACT LEFT7 CURRENCY RENEWABLE ENERGY Solana 100% USA (Arizona) 280 MW APS BBB+/Baa1/BBB+ 20 USD Mojave 100% USA (California) 280 MW PG&E BB/Ba1/BB+ 16 USD Coso 100% USA (California) 135 MW SCPPA & two CCAs4 Investment grade4 18 USD Elkhorn Valley8 49% USA (Oregon) 101 MW Idaho Power Company BBB/Baa1/-- 4 USD Prairie Star8 49% USA (Minnesota) 101 MW Great River Energy --/A3/A- 4 USD Twin Groves II8 49% USA (Illinois) 198 MW Exelon Generation Co. BBB+/Baa1/-- 2 USD Lone Star II8 49% USA (Texas) 196 MW n/a n/a n/a USD Chile PV 1 35% Chile 55 MW n/a n/a n/a USD3 Chile PV 2 35% Chile 40 MW n/a Not rated 7 USD3 Chile PV 3 35% Chile 73 MW n/a n/a n/a USD3 La Sierpe 100% Colombia 20 MW Coenersa6 Not rated 12 COP La Tolua 100% Colombia 20 MW Coenersa6 Not rated 9 COP Tierra Linda 100% Colombia 10 MW Coenersa6 Not rated 9 COP Honda 1 50% Colombia 10 MW Enel Colombia BBB-/---/BBB 7 COP Albisu 100% Uruguay 10 MW Montevideo Refrescos Not rated 14 UYU Palmatir 100% Uruguay 50 MW UTE BBB+/Baa1/BBB2 10 USD Cadonal 100% Uruguay 50 MW UTE BBB+/Baa1/BBB2 11 USD Melowind 100% Uruguay 50 MW UTE BBB+/Baa1/BBB2 12 USD Mini-Hydro 100% Peru 4 MW Peru BBB-/Baa1/BBB 9 USD3 Solaben 2/3 70% Spain 2x50 MW Kingdom of Spain A/Baa1/A- 13/14 EUR5 Solacor 1/2 87% Spain 2x50 MW Kingdom of Spain A/Baa1/A- 13/13 EUR5 Reflects the counterparties’ issuer credit ratings issued by S&P, Moody’s and Fitch, respectively, as of May 8, 2024. It refers to the credit rating of Uruguay, as UTE is unrated. USD denominated but payable in local currency. Refers to the credit rating of two Community Choice Aggregators: Silicon Valley Clean Energy and Monterrey Bay Community Power, both with A rating from S&P; Southern California Public Power Authority, the third off-taker, is not rated. AT A GLANCE Sizeable and Diversified Asset Portfolio (5) Gross cash in euros dollarized through currency hedges. (6) Largest electricity wholesaler in Colombia. (7) As of March 31, 2024. (8) Part of Vento II portfolio.

As of May 8, 2024 ASSET TYPE STAKE LOCATION GROSSCAPACITY OFFTAKER RATING1 YEARS INCONTRACT LEFT6 CURRENCY RENEWABLE ENERGY PS 10/20 100% Spain 31 MW Kingdom of Spain A/Baa1/A- 8/10 EUR4 Helioenergy 1/2 100% Spain 2x50 MW Kingdom of Spain A/Baa1/A- 13/13 EUR4 Helios 1/2 100% Spain 2x50 MW Kingdom of Spain A/Baa1/A- 13/13 EUR4 Solnova 1/3/4 100% Spain 3x50 MW Kingdom of Spain A/Baa1/A- 11/11/11 EUR4 Solaben 1/6 100% Spain 2x50 MW Kingdom of Spain A/Baa1/A- 14/14 EUR4 Seville PV 80% Spain 1 MW Kingdom of Spain A/Baa1/A- 12 EUR4 Italy PV 1 100% Italy 1.6 MW Italy BBB/Baa3/BBB 7 EUR4 Italy PV 2 100% Italy 2.1 MW Italy BBB/Baa3/BBB 7 EUR4 Italy PV 3 100% Italy 2.5 MW Italy BBB/Baa3/BBB 8 EUR4 Italy PV 4 100% Italy 3.6 MW Italy BBB/Baa3/BBB 7 EUR4 UK Wind 1 100% United Kingdom 25 MW United Kingdom AA / Aa3 / AA- 9 GBP UK Wind 2 100% United Kingdom 8 MW United Kingdom AA / Aa3 / AA- 4 GBP Kaxu 51% South Africa 100 MW Eskom BB-/Ba2/BB-2 11 ZAR EFFICIENT NAT. GAS & HEAT Calgary 100% Canada 55 MWt 22 High quality clients3 ~60% AA- or higher3 12 CAD ACT 100% Mexico 300 MW Pemex BBB/B3/B+ 9 USD5 TRANSMISSION LINES ATN 100% Peru 379 miles Peru BBB-/Baa1/BBB 17 USD5 ATS 100% Peru 569 miles Peru BBB-/Baa1/BBB 20 USD5 ATN 2 100% Peru 81 miles Minera Las Bambas Not rated 9 USD Quadra 1/2 100% Chile 49 miles / 32 miles Sierra Gorda Not rated 11/11 USD5 Palmucho 100% Chile 6 miles Enel Generacion Chile BBB/-/BBB+ 14 USD5 Chile TL 3 100% Chile 50 miles CNE A/A2/A- n/a USD5 Chile TL 4 100% Chile 63 miles Several Mini-hydro plants Not rated 48 USD WATER Skikda 34% Algeria 3.5 Mft3/day Sonatrach & ADE Not rated 10 USD5 Honaine 26% Algeria 7 Mft3/day Sonatrach & ADE Not rated 13 USD5 Tenes 51% Algeria 7 Mft3/day Sonatrach & ADE Not rated 16 USD5 Reflects the counterparties’ issuer credit ratings issued by S&P, Moody’s and Fitch, respectively, as of February 29, 2024. It refers to the credit rating of the Republic of South Africa. Diversified mix of 22 high credit quality clients (~60% AA- rating or higher, the rest unrated). AT A GLANCE Sizeable and Diversified Asset Portfolio (4) Gross cash in euros dollarized through currency hedges. (5) USD denominated but payable in local currency. (6) As of March 31, 2024.

Great West House, GW1, 17th floor, Great West Road Brentford TW8 9DF London (United Kingdom)

SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

| Atlantica Sustainable Infrastructure plc
Date: May 8, 2024 | By: | /s/ Santiago Seage
|  | Name: | Santiago Seage
|  | Title: | Chief Executive Officer