13. INCOME TAXES

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure Abstract

13. INCOME TAXES

13. INCOME TAXES

No provision for income taxes has been recorded for 2022, 2021 and 2020 due to the valuation allowances placed against the net operating losses and deferred tax assets arising during such periods. A valuation allowance has been recorded for all deferred tax assets. Based on our history of losses since inception, the available objective evidence creates sufficient uncertainty regarding the realizability of the deferred tax assets.

The effective tax rate of our provision (benefit) for income taxes differs from the Federal statutory rate as follows:

	Year Ended December 31,
	2022			2021			2020
Statutory rate		21.0	%		21.0	%		21.0	%
Compensation related		(0.5	)%		(8.2	)%		0.0	%
Share-based compensation		(2.2	)%		25.1	%		0.0	%
Net operating loss expiration		(9.0	)%		(16.2	)%		(47.5	)%
Tax credits		1.5	%		1.4	%		2.2	%
Change in valuation allowance		(10.8	)%		(23.1	)%		24.3	%
Total		0.0	%		0.0	%		0.0	%

Deferred tax assets are summarized as follows (in thousands):

	December 31,
	2022			2021
Deferred tax assets
Reserves	$	651		$	634
Net operating loss carryforwards		92,469			90,593
R&D credit carryforwards		9,628			8,984
Depreciation/amortization deferred		19,787			17,417
Operating lease liabilities		3,292			1,222
Other		7,360			6,701
Total deferred tax assets		133,187			125,551
Deferred tax liabilities:
Operating lease right-of-use assets		(3,062	)		(1,171	)
Total deferred tax liabilities		(3,062	)		(1,171	)
Net valuation allowances		(130,125	)		(124,380	)
Deferred tax assets	$	—		$	—

At December 31, 2022, we have net operating loss carryforwards of approximately $440.3 million for federal income tax reporting purposes. In addition, we have research and development tax credits of $9.6 million. During 2022, $22.0 million federal net operating losses and $171,000 general business credits expired unused. A majority of the net operating loss carryforwards and research and development credits available to offset future taxable income, if any, will expire in varying amounts from 2023 to 2042, if not previously used.

Certain net operating losses arise from the deductibility for tax purposes of compensation under nonqualified stock options equal to the difference between the fair value of the stock on the date of exercise and the exercise price of the options. For financial reporting purposes, the tax effect of this deduction, when recognized, is accounted for as an income tax benefit.

In certain circumstances, as specified in the Internal Revenue Code, a 50% or more ownership change by certain combinations of our shareholders during any three year period would result in limitations on our ability to use a portion of our net operating loss carryforwards.

We had no unrecognized tax benefits at December 31, 2022 or 2021.

We recognize interest accrued and penalties related to unrecognized tax benefits in tax expense. During the years ended December 31, 2022, 2021 and 2020 we recognized no interest or penalties.

We file income tax returns in the U.S. federal jurisdiction and Oregon. Due to our operating loss and credit carryforwards, the U.S. federal statute of limitations remains open for 1998 and onward.