INCOME TAXES (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Income before Income Tax and Current Taxes

Income (loss) before income taxes and the related tax expense is as follows (in thousands):



	Year Ended December 31,
	2018			2017			2016
Income (loss) before income taxes:
Domestic	$	5,169		$	(39,898	)	$	(36,339	)
Foreign	(5,594		)	(2,573		)	(1,505		)
Total loss before income taxes	$	(425	)	$	(42,471	)	$	(37,844	)

Current taxes:
Federal	$	(96	)	$	—		$	11
State	142			140			94
Total income tax expense	$	46		$	140		$	105

Schedule of reconciliation of income taxes at the U.S. Federal statutory rate to the provision for income taxes

A reconciliation of income taxes at the U.S. federal statutory rate to the provision for income taxes is as follows:



	Year Ended December 31,
	2018		2017		2016
U.S. federal statutory rate	21.00	%	35.00	%	35.00	%
State taxes	(24.84	)%	2.26	%	2.20	%
Foreign taxes	(92.04	)%	(1.28	)%	(0.81	)%
Change in valuation allowance	369.27	%	4.58	%	(43.96	)%
Stock-based compensation	(874.29	)%	(1.21	)%	(0.54	)%
Tax credits	700.35	%	4.96	%	8.77	%
Interest expense	218.47	%	2.90	%	5.75	%
Effect of rate changes	13.44	%	(130.88	)%	(4.65	)%
Convertible senior notes refinancing	—	%	6.55	%	—	%
Effect of the adoption of ASU 2016-09	—	%	68.89	%	—	%
Nondeductible expenses	(132.96	)%	—	%	—	%
Reserves	(202.98	)%	—	%	—	%
Other	(6.15	)%	7.90	%	(2.04	)%
Effective tax rate	(10.73	)%	(0.33	)%	(0.28	)%

Schedule of significant components of the Company's deferred tax assets

Deferred taxes reflect the tax effects of the differences between the amounts recorded as assets and liabilities for financial reporting purposes and the comparable amounts recorded for income tax purposes. Significant components of the Company’s deferred tax assets and liabilities at December 31, 2018 and 2017 are as follows (in thousands):



	December 31,
	2018			2017
Deferred tax assets:
Net operating loss carry-forwards	$	79,446		$	95,067
Federal and state credits	17,730			15,048
Depreciation and amortization	2,851			2,593
Accruals and reserves	11,009			2,743
Deferred revenue	—			1,841
Stock based compensation	18,302			16,925
Inventory	848			552
Other	127			139
Total deferred tax assets	130,313			134,908
Deferred tax liabilities:
Discount on convertible senior notes	(11,655		)	(14,678		)
Deferred tax assets, net of deferred tax liabilities	118,658			120,230
Less: valuation allowance	(118,658		)	(120,230		)
Net deferred tax assets	$	—		$	—

Schedule of Unrecognized Tax Benefits Roll Forward

The change in the Company’s UTBs in 2018 is summarized as follows (in thousands):



	Unrecognized Tax Benefit
Balance at December 31, 2017	$	2,473
Additions for current year positions	408
Balance at December 31, 2018	$	2,881