Ultragenyx Pharmaceutical Inc. Income Taxes Disclosure

The Company has incurred net operating losses since inception. The Company has not reflected any benefit of such net operating loss carryforwards in the accompanying financial statements. The Company has established a full valuation allowance against its deferred tax assets due to the uncertainty surrounding the realization of such assets.

For the year ended December 31, 2023, the Company recognized an income tax benefit of $5 million attributable to modifications in its state apportionment methodology, offset by an income tax expense of $3 million from foreign jurisdictions. For the year ended December 31, 2024, the Company recognized income tax expense of $1 million from foreign jurisdictions alongside a nominal amount of state tax. For the year ended December 31, 2025, the Company recognized income tax expense of $4 million from foreign jurisdictions and a nominal amount of state tax. The Company realized no benefit for current year losses due to a full valuation allowance against the U.S. net deferred tax assets.

The table below provides the updated requirements of ASU 2023-09 for the year ended December 31, 2025.

As of December 31, 2025 and 2024, the Company had approximately $2,104 million and $1,191 million, respectively, of federal net operating loss carryforwards available to reduce future taxable income that will begin to expire in 2031. As of December 31, 2025 and 2024, the Company had approximately $936 million and $744 million, respectively, of state net operating loss carryforwards available to reduce future taxable income that will begin to expire in 2031.

As of December 31, 2025 and 2024, the Company had federal research tax credit carryforwards of approximately $60 million and $45 million, respectively, available to reduce future tax liabilities that will begin to expire in 2031. As of December 31, 2025 and 2024, the Company had state research credit carryforwards of $110 million and $92 million, respectively, available to reduce future tax liabilities. The majority of these credits will be carried forward indefinitely, and others will expire at various dates in the future.

As of December 31, 2025 and 2024, the Company had federal Orphan Drug Credits of approximately $379 million and $339 million, respectively, available to reduce future tax liabilities that will begin to expire in 2031.

The Company’s ability to use net operating loss and tax credit carryforwards to reduce future taxable income and liabilities may be subject to annual limitations pursuant to Internal Revenue Code Sections 382 and 383 as a result of ownership changes in the past and future. As a result of ownership changes in 2012 and 2011, $4 million of federal net operating loss carryforwards, $4 million of state net operating loss carryforwards, and a nominal amount of federal tax credits are permanently limited. Deferred tax assets for net operating losses and tax credits have been reduced and a corresponding adjustment to the valuation allowance has been recorded.

The valuation allowance increased by $148 million and $171 million during the years ended December 31, 2025 and 2024, respectively.

The Company recorded unrecognized tax benefits for uncertainties in income taxes. A reconciliation of the Company’s unrecognized tax benefits follows (in millions):

Approximately $1 million in unrecognized tax benefits would impact the Company’s effective tax rate if recognized. The Company has elected to include interest and penalties as a component of tax expense. For the years ended December 31, 2025, 2024 and 2023, the Company recognized nominal amounts for accrued interest and penalties as a component of income tax expense. The Company does not anticipate that the amount of existing unrecognized tax benefits will significantly increase or decrease during the next year.

It is the Company’s intention to reinvest the earnings of its non-U.S. subsidiaries in their operations. As of December 31, 2025, the Company had not made a provision for any incremental foreign withholding taxes on approximately $17 million of the excess of the amount of net income for financial reporting over the tax basis of investments in foreign subsidiaries that are essentially permanent in duration. If these earnings were repatriated to the U.S., the deferred tax liability associated with these temporary differences would result in a nominal amount of withholding taxes.

The Company files income tax returns in the U.S. federal, 40 state tax jurisdictions, and ten foreign countries. The federal and state income tax returns from inception to December 31, 2025 remain subject to examination.