Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income Tax Disclosure [Abstract]

Components of Income Tax (Benefit) Expense

The following table summarizes the components of our income tax expense (benefit) for the periods presented (in thousands):

	Year Ended December 31,
	2021		2020		2019
Current income tax expense:
State	$	3,851	$	588	$	304
Foreign	143		257		99
Total current income tax expense	3,994		845		403
Deferred income tax benefit:
Federal	(2,577)		(7,388)		(1,631)
State	(302)		(1,095)		(2,856)
Foreign	148		115		(174)
Total deferred income tax benefit	(2,731)		(8,368)		(4,661)
Total income tax expense (benefit)	$	1,263	$	(7,523)	$	(4,258)

Reconciliation of Federal Statutory Rate and Effective Tax Rate

The following table presents a reconciliation of the federal statutory rate and our effective tax rate for the periods presented:

	Year Ended December 31,
	2021		2020		2019
Tax expense at federal statutory rate	(21.0)	%	(21.0)	%	(21.0)	%
State income taxes, net of federal tax benefit	(5.8)		(11.2)		(3.0)
Share-based compensation	(17.0)		(52.5)		(0.9)
Section 162(m) of Internal Revenue Code	1.7		2.3		1.1
Research and development credits	(8.5)		(10.6)		(7.2)
Other	0.9		(0.5)		1.0
Valuation allowance	49.9		89.1		28.6
Effective tax rate	0.2	%	(4.4)	%	(1.4)	%

Deferred Tax Assets and Liabilities

The following table presents the significant components of our deferred tax assets and liabilities as of the dates presented (in thousands):

	December 31,
	2021		2020
Deferred tax assets:
Federal and state net operating loss carryforwards	$	524,109	$	400,509
Research and development credits	133,173		88,823
Inventory	68,840		15,115
Share-based compensation	66,345		43,065
Interest expense limitation	58,155		30,921
Lease liability	41,402		57,606
Accruals and reserves	12,782		3,988
Depreciation and amortization	1,496		1,035
Other deferred tax assets	1,100		4,736
Total deferred tax assets	907,402		645,798
Deferred tax liabilities:
Debt discount on convertible senior notes	(60,448)		(80,280)
Website and software development costs	(43,814)		(32,021)
Right of use assets	(32,027)		(45,857)
Intangible assets	(21,697)		(12,968)
Goodwill	(4,631)		(3,267)
Total deferred tax liabilities	(162,617)		(174,393)
Net deferred tax assets before valuation allowance	744,785		471,405
Less: valuation allowance	(745,732)		(471,901)
Net deferred tax liabilities	$	(947)	$	(496)

Changes in Unrecognized Tax Benefits

Changes for unrecognized tax benefits for the periods presented are as follows (in thousands):

Balance at January 1, 2019	$	28,625
Gross increases—current period tax positions	9,021
Gross increases—prior period tax positions	1,786
Balance at December 31, 2019	$	39,432
Gross increases—current period tax positions	9,334
Gross increases—prior period tax positions	328
Balance at December 31, 2020	$	49,094
Gross increases—current period tax positions	16,627
Gross increases—prior period tax positions	9,257
Balance at December 31, 2021	$	74,978