Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of Provision for Income Taxes

There was no provision for the years ended December 31, 2017 and 2016. The following table presents components of the Company’s provision for income taxes as of December 31, 2018 (in thousands):

	Year Ended December 31, 2018
Current:
Federal	$	—
State	—
Foreign		80
Total current tax expense		80
Deferred:
Federal	—
State	—
Foreign		(36	)
Total deferred tax benefit		(36	)
Provision for income taxes	$	44

Reconciliation of Tax Expense Computed at Statutory Federal Rate and Company's Tax Expense

The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company’s tax expense for the period presented (in thousands):

	Year Ended December 31,
	2018			2017			2016
Tax at statutory federal rate		(10,143	)		(10,034	)	$	(7,107	)
Stock-based compensation		(8,562	)		(7,634	)	255
Meals and Entertainment		309		198			134
Other		149			(145	)	782
Tax credits		(1,015	)		(644	)		(139	)
2017 Tax Act		44			21,928		—
Change in valuation allowance		19,262			(3,669	)		6,075
Provision for income taxes	$	44		$	—		$	—

________________

⁽¹⁾ Due to the Tax Act which was enacted in December 2017, the Company recognized the remeasurement of deferred taxes with an offset to valuation.

Significant Components of Deferred Tax Assets and Liabilities

Significant components of the Company’s deferred tax assets and liabilities are as follows (in thousands):

	December 31,
	2018			2017
Deferred tax assets:
Net operating loss carryforwards	$	50,334		$	35,338
Tax credit carryforwards		4,287			2,642
Allowances and other		11,694			6,682
Depreciation and amortization		(388	)		(414	)
Total deferred tax assets		65,927			44,248
Valuation allowance		(65,886	)		(44,248	)
Net deferred tax assets	$	41		$	—

Summary of Valuation Allowance for Deferred Tax Assets

The valuation allowance for deferred tax assets consisted of the following activity for the years ended December 31, 2018, 2017 and 2016 (in thousands):

	Balance at beginning of year		Additions		Deductions		Balance at end of year
Year ended December 31, 2016	$	38,565	$	6,296	$	—	$	44,861
Year ended December 31, 2017		44,861		—		613		44,248
Year ended December 31, 2018	$	44,248	$	21,638	$	—	$	65,886

Reconciliation of Unrecognized Tax Benefit

A reconciliation of the Company’s unrecognized tax benefit amount is as follows (in thousands):

	Year Ended December 31,
	2018		2017			2016
Balance at beginning of year	$	943	$	616		$	570
Additions for tax positions taken in current year		441		328			75
Increases in balance related to prior year tax positions		75		—			—
Decreases in balances related to prior year tax position		—		(1	)		(29	)
Balance at end of year	$	1,459	$	943		$	616