Table of Contents ENPHASE ENERGY, INC. NOTES TO CONSOLIDATED FINANCIAL STATEMENTS The Company does not have any tax positions for which it is reasonably possible the total amount of gross unrecognized tax benefits will increase or decrease over the next year. The unrecognized tax benefits may increase or change during the next year for items that arise in the ordinary course of business. As of December 31, 2023, the total amount of gross unrecognized tax benefits was $27.2 million, of which $25.4 million, if recognized, would impact the Company’s effective tax rate. A tabular reconciliation of the total amounts of unrecognized tax benefits for the years presented is as follows (in thousands): Years Ended December 31, 2023 2022 2021 Unrecognized tax benefits—at beginning of year $ 21,768 $ 20,904 $ 8,421 Increases (decreases) in balances related to tax positions taken in prior years (417) (4,786) 4,391 Increases in balances related to tax positions taken in current year 5,985 6,562 8,301 Settlements — (657) — Lapses in statutes of limitations (118) (255) (209) Unrecognized tax benefits—at end of year $ 27,218 $ 21,768 $ 20,904 The Company includes interest and penalties related to unrecognized tax benefits within the income tax provision for (benefit from). In the year ended December 31, 2023, 2022 and 2021, the total amount of gross interest and penalties accrued was $2.9 million, $0.8 million and $0.3 million, respectively. Both the unrecognized tax benefits and the associated interest and penalties that are not expected to result in payment or receipt of cash within one year are classified as other non-current liabilities in the consolidated balance sheets. In connection with tax matters, the Company’s interest and penalty expense recognized in 2023, 2022 and 2021 in the consolidated statements of operations was $3.8 million, $0.9 million and $1.4 million, respectively. The Company’s tax returns continue to remain effectively subject to examination by U.S. federal authorities for the years 2006 and onwards and by California state authorities for the years 2006 and onwards due to use and carryovers of net operating losses and tax credits. The Company is currently under audit in India. In August 2022, the U.S. enacted the IRA, which included revisions to the Internal Revenue Code of 1986, as amended (the “Code”). The IRA introduced a 15% corporate alternative minimum income tax (“CAMT”) for corporations whose average adjusted financial income for any consecutive three-year period ending after December 31, 2021, exceeds $1.0 billion. Further, the IRA also extended the investment tax credits for clean energy and expanded the incentives to clean energy manufacturing. For the year ended December 31, 2023, the Company is not subject to the CAMT based on its current operating results and interpretations of the latest IRA guidance. The Company recognized $53.5 million reduction in costs of goods sold and income taxes payable related to the AMPTC. In December 2021, the Organization for Economic Co-operation and Development Inclusive Framework on Base Erosion Profit Shifting released Model Global Anti-Base Erosion rules (“Model Rules”) under Pillar Two. The Model Rules set forth the “common approach” for a Global Minimum Tax at 15 percent for multinational enterprises with a turnover of more than 750 million euros. Rules under Pillar Two were effective from January 1, 2024. The Company does not expect adoption of Pillar Two rules to have a significant impact on its consolidated financial statements in 2024. 18. CONCENTRATION OF CREDIT RISK AND MAJOR CUSTOMERS The Company is potentially subject to financial instrument concentration of credit risk through its cash, cash equivalents, marketable securities, and accounts receivable. The Company places its cash, cash equivalents and marketable securities with high quality institutions and performs periodic evaluations of their relative credit standing. Accounts receivable can be potentially exposed to a concentration of credit risk with its major customers. As of December 31, 2023 and 2022, amounts due from one customer represented approximately 40% and 24%, respectively, of the total accounts receivable balance. Enphase Energy, Inc. | 2023 Form 10-K | 119