Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

Income Taxes

    Loss before provision for income taxes includes the following components (in thousands):

	Year Ended December 31,
	2022		2021		2020
Domestic	$	(371,900)	$	(524,440)	$	(445,370)
Foreign	6,917		1,160		1,423
Loss before provision for income taxes	$	(364,983)	$	(523,280)	$	(443,947)

Provision for Income Taxes

    The provision for income taxes consists of the following (in thousands):

	Year Ended December 31,
	2022		2021		2020
Current:
Federal	$	—	$	—	$	—
State	(608)		50		165
Foreign	1,115		609		364
Total current income tax expense	507		659		529
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	2,708		(102)		(36)
Total deferred income tax expense	2,708		(102)		(36)
Provision for income taxes	$	3,215	$	557	$	493

Our income tax provision related to continuing operations differs from the amount computed by applying the statutory income tax rate of 21% to our pretax loss as follows (in thousands):

	Year Ended December 31,
	2022		2021		2020
Income tax benefit at federal statutory rate	$	(76,647)	$	(109,889)	$	(93,229)
Research credits	(987)		(4,727)		(3,081)
Change in valuation allowance	51,108		97,914		87,060
Expiration of net operating loss carryforwards	12,348		286		286
Stock-based compensation	15,778		6,627		7,929
Non-cash interest expense on liability related to sales of future royalties	6,071		9,936		6,356
Non-cash royalty revenue related to sales of future royalties	(7,112)		(7,891)		(7,967)
Loss on revaluation of liability related to the sale of future royalties	—		4,940		—
Other	2,656		3,361		3,139
Provision for income taxes	$	3,215	$	557	$	493

Deferred Tax Assets and Liabilities

    Deferred income taxes reflect the net tax effects of loss and credit carryforwards and temporary differences between the carrying amount of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. We measure deferred tax assets and liabilities based on the rates at which they are expected to reverse in the future. Significant components of our deferred tax assets for federal and state income taxes are as follows (in thousands):

	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	545,508	$	564,712
Research and other credits	142,198		139,996
Net capital loss carryforwards	38,445		—
Operating lease liabilities	28,254		34,680
Stock-based compensation	22,110		33,408
Capitalized research and development costs	24,134		—
Liability related to the sale of future royalties	13,424		23,757
Other	13,935		17,290
Deferred tax assets before valuation allowance	828,008		813,843
Valuation allowance for deferred tax assets	(816,235)		(785,748)
Total deferred tax assets	11,773		28,095
Deferred tax liabilities:
Operating lease right-of-use assets	(11,335)		(27,204)
Investment in foreign subsidiary	(2,451)		—
Other	(392)		(564)
Total deferred tax liabilities	(14,178)		(27,768)
Net deferred tax assets (liabilities)	$	(2,405)	$	327

    Realization of our deferred tax assets is dependent upon future earnings, if any, the timing and amount of which are uncertain. Because of our lack of U.S. earnings history, other than income resulting from revenue recognized from the BMS Collaboration Agreement, and projected future losses, we have fully reserved our net U.S. deferred tax assets with a valuation allowance. The valuation allowance increased by $30.5 million and $115.6 million during the years ended December 31, 2022 and 2021, respectively.

Our net deferred tax liability position reflects the provision for the withholding taxes associated with the repatriation of accumulated earnings and profits from India.

    Net Operating Loss and Tax Credit Carryforwards

    As of December 31, 2022, we had a net operating loss carryforward for federal income tax purposes of approximately $2.4 billion, of which $1.3 billion is subject to expiration beginning in 2023 and a total state net operating loss carryforward of approximately $0.7 billion, portions of which will begin to expire in 2027. We have federal tax credits of approximately $123.8 million, which will begin to expire in 2023 and state research credits of approximately $48.8 million which have no expiration date. Utilization of some of the federal and state net operating loss and credit carryforwards are subject to annual limitations due to the “change in ownership” provisions of the Internal Revenue Code of 1986 and similar state provisions.

Unrecognized tax benefits

    We have the following activity relating to unrecognized tax benefits (in thousands):

	Year Ended December 31,
	2022		2021		2020
Beginning balance	$	80,604	$	78,665	$	77,410
Tax positions related to current year:
Additions	378		2,371		2,512
Reductions	—		—		—
Tax positions related to prior years:
Additions	5,272		58		193
Reductions	—		(490)		(1,450)
Settlements	—		—		—
Lapses in statute of limitations	(409)		—		—
Ending balance	$	85,845	$	80,604	$	78,665

    If we are eventually able to recognize our uncertain tax positions, our effective tax rate may be reduced. We currently have a full valuation allowance against our U.S. net deferred tax asset which would impact the timing of the effective tax rate benefit should any of these uncertain tax positions be favorably settled in the future. Adjustments to the substantial majority of our uncertain tax positions would result in an adjustment of our net operating loss or tax credit carryforwards rather than resulting in a cash outlay.

    We file income tax returns in the U.S., California, Alabama, certain other states and India. As a result of our net operating loss and research credit carryforwards, substantially all of our domestic tax years remain open and subject to examination. We may be subject to examination in India from time to time, but we do not believe that any liability resulting from such an examination would have a material effect on our financial position or results of operations.

Our policy is to include interest and penalties related to unrecognized tax benefits, if any, within the provision for income taxes in the consolidated statements of operations. During the years ended December 31, 2022, 2021 and 2020, no significant interest or penalties were recognized relating to unrecognized tax benefits. Although it is reasonably possible that certain unrecognized tax benefits could change in the future, we do not anticipate any significant changes over the next twelve months.