Income Taxes
The Company had no income tax expense due to operating losses incurred for the years ended December 31, 2024 and 2023.
A reconciliation of the income tax expense computed using the federal statutory income tax rate to the Company’s effective income tax rate is as follows:
Year Ended
December 31,
20242023
Income tax computed at federal statutory tax rate21.0 %21.0 %
State taxes, net of federal benefit4.9 %6.0 %
General business credit carryovers2.6 %2.5 %
162m limitation(0.2)%— %
Stock options(0.2)%(4.3)%
Non-deductible expenses(0.1)%(0.2)%
Tax rate changes(2.6)%(4.5)%
Change in valuation allowance(25.5)%(21.8)%
Other— %1.3 %
(0.1)%— %
The principal components of the Company’s deferred tax assets and liabilities consist of the following at December 31, 2024 and 2023 (in thousands):
Year Ended
December 31,
20242023
Deferred tax assets:
Net operating loss carryforwards$170,770 $153,365 
Tax credit carryforwards31,766 25,646 
Accrued expenses6,763 3,975 
Capitalized patent costs52,178 56,955 
Capitalized research84,703 60,891 
Lease liabilities9,134 9,966 
Deferred revenue15,755 18,791 
Depreciation and amortization978 905 
Stock compensation10,431 7,323 
Other14,976 — 
Total deferred tax assets397,454 337,817 
Less valuation allowance(388,967)(328,630)
Net deferred tax assets8,487 9,187 
Deferred tax liabilities(8,487)(9,187)
Depreciation and amortization— — 
Right-of-use assets(8,487)(9,187)
Net deferred taxes$— $— 
For taxable years beginning after December 31, 2021, the Tax Cuts and Jobs Act (the "Tax Act”) eliminated the option to deduct research and development expenditures in the current year and requires taxpayers to capitalize such expenses pursuant to Internal Revenue Code ( "IRC" ) Section 174. As a result of this provision of the Tax Act, deferred tax assets related to capitalized research expenses pursuant to IRC Section 174 was $84.7 million for the year ended December 31, 2024.
The Company has incurred net operating losses (“NOL”) since inception. At December 31, 2024 and 2023, the Company had federal net operating loss carryforwards of $612.8 million and $546.7 million, respectively. Of the amount as of December 31, 2024, $538.1 million will carryforward indefinitely while $74.8 million will expire beginning in 2035 and will continue to expire through 2037. As of December 31, 2024, and 2023, the Company also had state net operating loss carryforwards of approximately $710.5 million and $648.0 million, respectively, which may be available to offset future income tax liabilities and will expire beginning in 2035 and will continue to expire through 2044.
Under the provisions of the Internal Revenue Code of 1986, as amended (the “Code”), the NOL and tax credit carryforward are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. NOL and tax credit carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Code, respectively, as well as other similar state provisions. The Company conducted an analysis under Section 382 to determine if historical changes in ownership through June 30, 2024 would limit or otherwise restrict its ability to utilize its NOL and research and development credit carryforwards. As a result of this analysis, the Company does not believe there are any significant limitations on its ability to utilize these carryforwards. However, future changes in ownership occurring after June 30, 2024 could affect the limitation in future years, and any limitation may result in expiration of a portion of the NOL or research and development credit carryforwards before utilization.
Management has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which principally comprise of NOL carryforwards, research and development credit carryforwards and capitalized license and patent costs. The Company’s management has determined that it is more likely than not that the Company will not recognize the benefits of its federal and state deferred tax assets, and as a result, a valuation allowance of $389.0
million and $328.6 million has been established at December 31, 2024 and 2023, respectively. The increase in the valuation allowance of $60.3 million for the year ended December 31, 2024 was primarily due to current period pre-tax losses incurred and research tax credits generated.
The Company applies ASC 740 related to accounting for uncertainty in income taxes. The Company’s reserves related to income taxes are based on a determination of whether, and how much of, a tax benefit taken by the Company in its tax filings or positions is more likely than not to be realized following resolution of any potential contingencies present related to the tax benefit.
The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2024 and 2023 (in thousands):
Year Ended
December 31, 2024
Balance as of December 31, 2023$13,659 
Gross increases for tax positions related to current year2,020 
Gross increases for tax positions related to prior year— 
Balance as of December 31, 2024$15,679 
At December 31, 2024 and 2023, the Company had unrecognized tax benefits of $15.7 million and $13.7 million, respectively. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2024 and 2023, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s statement of operations. The Company does not anticipate a material change to unrecognized tax benefits in the next twelve months.
The Company has not as of yet conducted a study of its research and development credit carry forwards. This study may result in an adjustment to the Company’s research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits, and if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheets or statements of operations if an adjustment were required.
The Company files income tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. Since the Company is in a loss carryforward position, the Company is generally subject to examination by the U.S. federal, state and local income tax authorities for all tax years in which a loss carryforward is available. The Company did not have any international operations as of December 31, 2024. An examination by the Internal Revenue Service (“IRS”) for the period ended December 31, 2018 related to its R&D tax credits concluded in December 31, 2022 and resulted in a reduction to the Company’s deferred tax assets.

About Income Taxes Disclosures

The income tax disclosure reveals how much a company actually pays in taxes versus what the statutory rate would predict. Analysts focus on the effective tax rate (ETR) reconciliation, which breaks down every item driving the gap between the 21% federal rate and the company's reported ETR — including R&D credits, foreign rate differentials, and state taxes. Deferred tax assets (DTAs) and their valuation allowances signal management's confidence in future profitability: a rising allowance suggests the company doubts it can use accumulated tax benefits. Uncertain tax benefit (UTB) reserves quantify exposure to IRS challenges on aggressive positions.

Key signals to watch: sudden ETR drops without clear operational reasons, large increases in valuation allowances, growing UTB balances, and significant unremitted foreign earnings. Post-TCJA, pay attention to GILTI and BEAT provisions that affect multinational tax structures. Compare the cash taxes paid (from the cash flow statement) against the income tax provision to gauge earnings quality.