RAMBUS INC Income Taxes Disclosure

18. Income Taxes

The table below provides the updated requirements of ASU 2023-09 for 2025. See Note 3, “Recent Accounting Pronouncements,” for additional details on the adoption of ASU 2023-09.

As previously disclosed for the years ended December 31, 2024 and 2023, prior to the adoption of ASU 2023-09, the effective income tax rate differs from the statutory federal income tax rate as follows:

Income Tax Payments

The Company periodically evaluates the realizability of its net deferred tax assets based on all available evidence, both positive and negative. The realizability of the Company’s net deferred tax assets is dependent on its ability to generate sufficient future taxable income during periods prior to the expiration of tax attributes to fully utilize these assets. During 2023, based on all available positive and negative evidence, the Company determined that it was appropriate to release the valuation allowance on the majority of the Company’s U.S. federal and other state deferred tax assets. The Company recognized a $177.9 million tax benefit during the year ended December 31, 2023 as a result of the valuation allowance release.

Upon considering the relative impact of all evidence during 2025, both negative and positive, and the weight accorded to each, the Company concluded that it was more likely than not that the majority of its deferred tax assets would be realizable, with the exception of primarily its California research and development credits that have not met the “more likely than not” realization threshold criteria. As a result, the Company continues to maintain a valuation allowance on only those deferred tax assets that it does not think will be realizable.

As of December 31, 2025, the Company had California net operating loss carryforwards of $171.9 million. As of December 31, 2025, the Company had federal research and development tax credit carryforwards of $48.9 million and foreign tax credits of $1.3 million. As of December 31, 2025, the Company had California research and development tax credit carryforwards of $32.6 million and California alternative minimum tax credit carryforwards of $0.5 million. The federal research and development tax credits and the foreign tax credits will continue to carry over and begin to expire in 2028, if unused. The California net operating losses begin to expire in 2031. The California research and development credits carry forward indefinitely.

In the event of a change in ownership, as defined under federal and state tax laws, the Company’s net operating loss and tax credit carryforwards could be subject to annual limitations. The annual limitations could result in the expiration of the net operating loss and tax credit carryforwards prior to utilization.

As of December 31, 2025, the Company had $108.0 million of unrecognized tax benefits, before interest accrual, including $24.3 million recorded as a reduction of long-term deferred tax assets, $82.7 million recorded as a reduction of other assets associated with refundable withholding taxes previously withheld from licensees in South Korea and $1.0 million recorded to long-term income taxes payable.

On September 18, 2025, the South Korean Supreme Court ruled that the use of any patents in South Korea constitutes domestic source income under the South Korea–U.S. Tax Treaty, even if such patents are not registered with the patent office in South Korea. Based on this ruling, patent license royalties are subject to South Korean withholding tax if the patents are used in South Korea. As a result of this ruling, Rambus determined that it is not more likely than not that withholding taxes paid in South Korea are recoverable.

The Company previously filed refund claims for withholding taxes paid in South Korea in the amount of $82.7 million related to the period from the fourth quarter of 2018 through the third quarter of 2023. The Company previously intended to file additional refund claims in the future for $32.2 million of withholding taxes paid from the fourth quarter of 2023 through the second quarter of 2025. The Company had previously recorded a long-term taxes receivable of $114.9 million and $105.1 million, before interest accrual, related to these refund claims as of June 30, 2025 and December 31, 2024, respectively. If the South Korea withholding taxes are recovered through the refund claim process, the U.S. foreign tax credit claimed for these withholding taxes on historical federal tax returns will be forfeited. Therefore, the Company had also recorded a long-term taxes payable of $114.9 million and $105.1 million as of June 30, 2025 and December 31, 2024, respectively. These amounts excluded interest and reflected the future U.S. federal tax liability in the event of filing amended federal tax returns to revise the foreign tax credit amounts. The recovery of South Korea withholding taxes paid before the fourth quarter of 2018 of $74.8 million was uncertain due to the statute of limitations for filing a refund claim. Thus, the Company did not previously record a long-term taxes receivable and included this amount in the uncertain tax benefit.

As a result of the September 2025 ruling, the Company recorded an uncertain tax position reserve on the $82.7 million of outstanding refund claims, reducing the previously recorded long-term taxes receivable for these refund claims to zero, as it determined it is not more likely than not that the withholding taxes paid in South Korea are recoverable. The Company also removed the $32.2 million long-term taxes receivable previously recorded for withholding taxes paid during the fourth quarter

of 2023 through the second quarter of 2025. As a result, the total long-term taxes receivable balance of $114.9 million, excluding interest, was reduced to zero in the third quarter of 2025. The related long-term taxes payable of $114.9 million, excluding interest, was also reduced to zero, resulting in zero tax expense impact.

Additionally, the Company’s future effective tax rates could be adversely affected by earnings being higher than anticipated in countries where the Company has higher statutory rates or lower than anticipated in countries where it has lower statutory rates, by changes in valuation of its deferred tax assets and liabilities or by changes in tax laws or interpretations of those laws.

As of December 31, 2024, the Company had $203.8 million of unrecognized tax benefits, before interest accrual, including $22.8 million recorded as a reduction of long-term deferred tax assets, $74.8 million recorded as a reduction of other assets associated with refundable withholding taxes previously withheld from licensees in South Korea and $106.2 million recorded to long-term income taxes payable, which were primarily comprised of $105.1 million in income taxes payable related to withholding taxes previously withheld from licensees in South Korea.

The Company recognizes interest and penalties related to uncertain tax positions as a component of the income tax provision (benefit). As of December 31, 2025 and 2024, an immaterial amount of interest and penalties was included in long-term income taxes payable.

Rambus files income tax returns for the U.S., California, India and various other state and foreign jurisdictions. The U.S. federal returns are subject to examination from 2022 and forward. The Company’s 2023 federal return is currently under audit by the Internal Revenue Service. The California returns are subject to examination from 2021 and forward. In addition, any research and development credit carryforward or net operating loss carryforward generated in prior years and utilized in these or future years may also be subject to examination. The India returns are under examination by the Indian tax administration for tax years beginning with 2011, except for 2012 through 2016, which were assessed in the Company’s favor, and are subject to examination from 2017 and forward. These examinations may result in proposed adjustments to the income taxes as filed during these periods. Management regularly assesses the likelihood of outcomes resulting from income tax examinations to determine the adequacy of their provision for income taxes and believes their provision for unrecognized tax benefits is adequate.

As of December 31, 2025, no other income taxes (state or foreign) have been provided on undistributed earnings of approximately $59.1 million from the Company’s international subsidiaries since these earnings have been, and under current plans will continue to be, indefinitely reinvested outside the United States, with the exception of France. If the non-France earnings were distributed, the Company would incur approximately $1.3 million of foreign withholding taxes and an immaterial amount of U.S. taxes.

On July 4, 2025, the United States enacted federal tax legislation commonly referred to as the OBBBA. Included in this legislation are provisions that allow for the immediate expensing of domestic United States research and development expenses, immediate expensing of certain capital expenditures and other changes to the U.S. taxation of profits derived from foreign operations. As a result of the enactment of the legislation, there was an increase to tax expense, primarily related to

changes in the taxation of profits derived from foreign operations and, more specifically, the foreign-derived intangible income deduction.