Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

14. Income Taxes

Our pre-tax book loss was derived from our business operations within the United States.

A reconciliation of our effective tax rate to the statutory U.S. federal rate is as follows:

	Year Ended December 31,
	2023			2022			2021
Statutory rate		21.0	%		21.0	%		21.0	%
Stock-based compensation		0.5	%		1.5	%		2.2	%
Credits		1.4	%		0.8	%		1.1	%
Change in valuation allowance		(21.8	)%		(21.3	)%		(23.0	)%
Section 162(m) limitation		(1.1	)%		(1.8	)%		(1.1	)%
Other		0.0	%		(0.2	)%		(0.2	)%
Total		0.0	%		0.0	%		0.0	%

Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of the assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The following table presents significant components of our deferred tax assets as of December 31, 2023 and 2022:

	As of December 31,
	2023			2022
	(in thousands)
Deferred tax assets:
Net operating losses		135,298			111,555
Fixed assets		660			1,062
Accrued and others		11,279			1,103
R&D Credits		12,870			5,436
Capitalized R&D expenditures		79,485			32,873
Accrued manufacturing expenses		10,819			2,063
Lease liability		8,739			5,358
Intangible assets		29,302			6,867
Stock compensation		8,981			4,474
Total deferred tax assets		297,434			170,791
Deferred tax liabilities:
ROU asset		(9,269	)		(6,357	)
Total deferred tax liabilities		(9,269	)		(6,357	)
Net deferred tax asset		288,165			164,433
Valuation allowance		(288,165	)		(164,433	)
Net deferred taxes	$	—		$	—

At December 31, 2023, we have net operating loss (“NOL”) carryforwards of approximately $351.9 million and $693.6 million available to reduce future taxable income, if any, for federal and state income tax purposes, respectively. The federal and state NOL carryforwards, except the federal loss carryforward arising in tax years beginning after December 31, 2017, begin to expire in 2034 unless previously utilized. Federal NOLs arising in tax years beginning after December 31, 2017 have an indefinite carryover period and do not expire.

At December 31, 2023, we have research credit carryforwards of $12.8 million and $4.6 million available to offset future income tax liabilities, if any, for federal and California income tax purposes, respectively. The federal research and development tax credit carryforwards expire beginning in 2039 unless previously utilized. The California tax credits can be carried forward indefinitely.

We have evaluated the positive and negative evidence bearing upon the realizability of our deferred tax assets. Based on our history of operating losses, we have concluded that it is more likely than not that the benefit of our deferred tax assets will not be realized. Accordingly, we have provided a full valuation allowance for deferred tax assets as of December 31, 2023 and 2022.

Utilization of the NOL and research credit carryforward may be subject to an annual limitation due to the ownership percentage change limitations under Section 382 and Section 383, respectively, provided by the Internal Revenue Code of 1986, as amended (the “Code”), and similar state provisions. The annual limitation may result in the expiration of the NOL before utilization. We have experienced ownership changes in the past. There were no ownership changes identified in 2023, as such we have determined that no federal research credits will expire unutilized or are excluded from our research credit carryforwards. Subsequent ownership changes may affect the limitation in future years.

We have uncertain tax benefits (“UTBs”) totaling $4.4 million and $1.8 million as of December 31, 2023 and 2022, respectively, which were netted against deferred tax assets subject to valuation allowance. The UTBs had no effect on the effective tax rate. We recognize interest and penalties related to UTBs, when they occur, as a component of income tax expense. To the extent accrued interest and penalties do not ultimately become payable, amounts accrued will be reduced and reflected as a reduction of the provision for income taxes in the period such determination is made. There were no interest or penalties recognized for the years ended December 31, 2023 and 2022. We do not expect our UTBs to change significantly over the next 12 months.

A reconciliation of the beginning and ending unrecognized tax benefit amount is as follows:

	December 31,
	2023		2022			2021
	(in thousands)
Balance at the beginning of the year	$	1,754	$	924		$	393
Additions based on tax positions related to current year		2,208		876			461
Additions based on tax positions related to prior years		485		(46	)		70
Balance at end of year	$	4,447	$	1,754		$	924

We file U.S. federal and state tax returns. In general, the Company is no longer subject to tax examination by the Internal Revenue Service or state taxing authorities for years before 2019. Although the federal and state statutes are closed for purposes of assessing additional income tax in those prior years, the taxing authorities may still make adjustments to the NOL and credit carryforwards used in open years. Therefore, the tax statutes should be considered open as it relates to the NOL and credit carryforwards used in open years. We do not have any tax audits or other issues pending.

In accordance with the 2017 Tax Act, research and experimental (“R&E”) expenses under Internal Revenue Code Section 174 are required to be capitalized beginning in 2022. R&E expenses are required to be amortized over a period of five years for domestic expenses and 15 years for foreign expenses. The Company has capitalized research and experimental expenditures in its current tax provision as a result.

The Inflation Reduction Act of 2022 specifically introduces the topic of corporate alternative minimum tax on adjusted financial statement income on applicable corporations for taxable years beginning after December 31, 2022. There is no impact to the Company’s current tax provision.

The American Rescue Plan Act was signed on March 11, 2021. One of the provisions of the Act included expanding the definition of covered employees subject to IRC 162(m) to include an additional top five highest compensated officers beyond the CEO, CFO, and three highest paid employees currently covered under IRC 162(m). This expanded provision is applicable for tax years beginning after December 31, 2026. We do not believe that this update to IRC 162(m) would have a material impact on its income tax provision currently and will continue to monitor this.