
	Year Ended December 31,
(in millions)	2020		2019		2018
Current:
Federal	$	—	$	—	$	(0.1)
State	10.1		9.5		0.8
Total current taxes	10.1		9.5		0.7
Deferred:
Federal	(287.5)		—		—
State	(23.2)		—		—
Total deferred taxes	(310.7)		—		—
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7


	Year Ended December 31,
(in millions)	2020		2019		2018
Federal income taxes at 21% for 2020, 2019, 2018	$	22.4	$	9.8	$	4.6
State income tax, net of federal benefit	5.5		4.0		0.4
Non-deductible expenses	0.6		0.8		0.4
Branded prescription drug fee	4.9		3.7		—
Share-based compensation expense	(6.7)		(12.8)		(9.8)
Officer compensation	3.7		3.1		0.9
Change in tax rate	3.3		(4.1)		(0.2)
Expired tax attributes	1.1		1.2		13.9
Research credits	(39.0)		(10.4)		(13.5)
Change in valuation allowance	(296.3)		13.9		4.3
Other	(0.1)		0.3		(0.3)
(Benefit from) provision for income taxes	$	(300.6)	$	9.5	$	0.7


	December 31,
(in millions)	2020		2019
Deferred tax assets:
Net operating losses	$	111.4	$	181.3
Research and development credits	109.6		71.9
Capitalized research and development	24.7		28.0
Share-based compensation expense	29.8		22.9
Operating lease assets	25.2		23.3
Intangible assets	86.7		49.3
Other	23.9		18.5
Total deferred tax assets	411.3		395.2
Deferred tax liabilities:
Convertible senior notes	(13.8)		(24.1)
Operating lease liabilities	(19.9)		(18.2)
Other	(8.4)		(6.9)
Total deferred tax liabilities	(42.1)		(49.2)
Net of deferred tax assets and liabilities	369.2		346.0
Valuation allowance	(49.8)		(346.0)
Net deferred tax assets	$	319.4	$	—

At December 31, 2020, our deferred tax assets were primarily the result of federal net operating loss carry forwards, capitalized research costs, acquired intangible assets and tax credit carryforwards. At December 31, 2020 and 2019, we recorded a valuation allowance of $49.8 million and $346.0 million, respectively, against our gross deferred tax asset balance.

At each reporting date, management considers new evidence, both positive and negative, that could affect its assessment of the future realizability of our deferred tax assets. At December 31, 2020, in part because we achieved three years of cumulative pretax income, management determined there is sufficient positive evidence to conclude that it is more likely than not deferred tax assets of $319.4 million are realizable. Accordingly, we recorded a net valuation release of $296.3 million on the basis of management’s assessment. The remaining valuation allowance of $49.8 million consists primarily of state net operating loss and credit carryforwards for which management cannot conclude it is more likely than not to be realized. The release of the valuation allowance is reported under continuing operations as a benefit to income tax expense.

At December 31, 2020, we had federal and state income tax net operating loss carryforwards of $518.2 million and $340.8 million, respectively. The federal net operating losses will begin to expire in 2028, unless previously utilized.

California net operating losses will begin to expire in 2028 unless previously utilized and the net operating losses related to other states will begin to expire in 2026.

In addition, we have federal and California R&D tax credit carryforwards of $92.1 million and $56.4 million, respectively. A portion of the federal R&D tax credit carryforwards expired in 2020. The remaining federal R&D tax credits will continue to expire beginning in 2021, unless previously utilized. The California R&D tax credits carry forward indefinitely.

Additionally, the future utilization of our net operating loss and R&D tax credit carryforwards to offset future taxable income may be subject to an annual limitation, pursuant to Internal Revenue Code Sections 382 and 383, as a result of ownership changes that could occur in the future. No ownership changes have occurred through December 31, 2020.

The impact of an uncertain income tax position on the income tax return must be recognized at the largest amount that is more-likely-than-not to be sustained upon audit by the relevant taxing authority. An uncertain income tax position will not be recognized if it has less than a 50% likelihood of being sustained.

Our policy is to recognize interest or penalties related to income tax matters in income tax expense. Interest and penalties related to income tax matters were not material for 2020, 2019 or 2018.

We are subject to taxation in the U.S. and various state jurisdictions. Our tax years for 2001 (federal) and 2008 (California) and forward are subject to examination by federal and state tax authorities due to the carryforward of unutilized net operating losses and R&D tax credits.


	Year Ended December 31,
(in millions)	2020		2019		2018
Balance at January 1	$	63.9	$	54.8	$	37.4
(Decrease) increase related to prior year tax positions	(5.7)		0.3		6.1
Increase related to current year tax positions	3.9		9.5		11.7
Settlements related to prior year tax positions	(0.2)		—		—
Expiration of the statute of limitations for the assessment of taxes	(1.1)		(0.7)		(0.4)
Balance at December 31	$	60.8	$	63.9	$	54.8

We excluded those deferred tax assets that are not more-likely-than-not to be sustained under the technical merits of the tax position. Such unrecognized tax benefits total $3.9 million for current year tax positions, as reflected in the table above.

At December 31, 2020, we had $53.9 million of unrecognized tax benefits that, if recognized and realized, would affect the effective tax rate, subject to the valuation allowance. We do not expect a significant change in our unrecognized tax benefits in the next twelve months.