Whitehawk Therapeutics, Inc. Income Taxes Disclosure

12. Income Taxes

The Company recorded no income tax expense or benefit for the years ended December 31, 2025 and 2024 due to the Company's net and comprehensive losses and increases in its deferred tax asset valuation allowance. The Company's operations are solely related to domestic operations for the years ended December 31, 2025 and 2024. Additionally, the Company did not pay any material federal or state cash income taxes or have cash income tax refunded for the year ended December 31, 2025.

Deferred income tax assets and liabilities are recorded for differences between the financial statement and tax basis of the assets and liabilities that will result in taxable or deductible amounts in the future based on enacted laws and rates applicable to the periods in which the differences are expected to affect taxable income. Valuation allowances are established when necessary to reduce deferred tax assets to the amount expected to be realized in future periods.

The Company has evaluated the available evidence supporting the realization of its gross deferred tax assets, including the amount and timing of future taxable income and has determined it is more likely than not that the assets will not be realized. As a result, the Company has concluded that a full valuation allowance against its deferred tax asset is necessary at this time.

As of December 31, 2025, the Company has federal and state net operating loss (“NOL”) carryforwards of $118.9 million and $22.2 million, respectively. Of the amount of federal and state NOL carryforwards, $78.3 million and $0.9 million, respectively, can be carried forward indefinitely. The remaining federal and state NOL carryforwards begin to expire in 2030 and 2037, respectively, unless previously utilized. The Company also has federal and state research credit carryforwards of approximately $1.2 million and $0.2 million, respectively, as of December 31, 2025. The federal and New Jersey research credit carryforwards will begin to expire in 2045 and 2032, respectively, unless previously utilized. The California research and development (“R&D”) credit will carry forward indefinitely. The decrease in the valuation allowance is $77.3 million and the increase in valuation allowance is $49.8 million for the years ended December 31, 2025 and 2024, respectively.

Pursuant to Section 382 and 383 of the Internal Revenue Code (“IRC”), utilization of the Company’s NOL carryforwards and R&D credits may be subject to annual limitations in the event of any significant future changes in its ownership structure. These annual limitations may result in the expiration of NOL carryforwards and R&D credits prior to utilization. The Company has completed an IRC section 382 analysis through December 31, 2024 and has identified ownership changes occurred on August 26, 2021 and February 28, 2017. These ownership changes will impose annual limits on the amounts of NOLs and R&D credits available at the ownership change dates, however assuming the Company does not experience future ownership changes and there is adequate taxable income to absorb the existing NOLs and R&D credits, none of these existing tax attributes are projected to expire before utilization. Future ownership changes occurring subsequent to December 31, 2024 may cause NOL and R&D credit carryforwards to expire unused and, if so, such tax attributes will be removed from the deferred tax asset table above.

On July 4, 2025, the U.S. President signed into law H.R.1, the legislation commonly known as the One Big Beautiful Bill Act (OBBBA). This legislation extended, modified, or made permanent many of the tax provisions which were initially enacted as part of the Tax Cuts and Jobs Act (TCJA) of 2017. The OBBBA contains a number of tax provisions including, but not limited to, immediate expensing of domestic research and experimental expenditures, modifications to the limitation on business interest, bonus depreciation modifications, as well as international tax provision modifications. These tax

provisions apply to either tax years beginning after December 31, 2024 or December 31, 2025. The Company has reflected the effect of OBBBA within the provision for income taxes and the deferred taxes as of December 31, 2025.

Uncertain tax positions are evaluated based upon the facts and circumstances that exist at each reporting period. Subsequent changes in judgment based upon new information may lead to changes in recognition, derecognition, and measurement. Adjustment may result, for example, upon resolution of an issue with the taxing authorities or expiration of a statute of limitations barring an assessment for an issue.

The Company recognizes a tax benefit from an uncertain tax position when it is more likely than not that the position will be sustained upon examination by tax authorities.

Due to the existence of the valuation allowance, future recognition of previously unrecognized tax benefits will not impact the Company’s effective tax rate. The Company’s practice is to recognize interest and penalties related to income tax matters in income tax expense. The Company is subject to taxation in the United States federal and certain state jurisdictions. The Company’s tax years from inception are subject to examination by the United States federal and state authorities due to the carryforward of unutilized NOLs and R&D credits. The Company does not anticipate the unrecognized tax benefits to change materially within the next twelve months.

The Company had no accrued interest and no penalties related to income tax matters in the Company’s balance sheet as of December 31, 2025 and has not recognized interest or penalties in the Company’s statement of operations and loss for the year ended December 31, 2025. Further, the Company is not currently under examination by any federal, state or local tax authority.