Income Taxes (Tables)

12 Months Ended

Mar. 31, 2015

A reconciliation of income tax (benefit) expense to the federal statutory rate follows (in thousands):

	Year Ended March 31,
	2015			2014			2013
Federal income tax at the statutory rate	$	(10,681	)	$	(5,452	)	$	(7,436	)
State taxes, net of federal effect		(671	)		(93	)		(661	)
Foreign taxes		33			134			675
R&D tax credit		(392	)		37			(1,157	)
Impact of state rate change		(2,627	)		492			838
Warrant liability		—			(3	)		(299	)
Expiring NOL		3,865			1,543			—
Valuation allowance		10,583			3,614			(1,877	)
Excess tax benefit—stock compensation		—			—			10,383
Other		7			(52	)		228

Income tax expense (benefit)	$	117		$	220		$	694

The Company's deferred tax assets and liabilities consisted of the following at March 31, 2015 and 2014 (in thousands):

	2015			2014
Deferred tax assets:
Inventories	$	3,323		$	2,152
Warranty reserve		1,217			1,051
Bad debt reserve		4,223			803
Deferred revenue		953			731
Net operating loss ("NOL") carryforwards		218,826			214,071
Tax credit carryforwards		18,860			18,369
Depreciation, amortization and impairment loss		3,231			3,631
Other		5,154			4,477

Deferred tax assets		255,787			245,285
Valuation allowance for deferred tax assets		(246,753	)		(236,169	)

Deferred tax assets, net of valuation allowance		9,034			9,116
Deferred tax liabilities:
Federal benefit of state taxes		(9,034	)		(9,116	)

Net deferred tax assets	$	—		$	—

The Company's NOL and tax credit carryforwards for federal and state income tax purposes at March 31, 2015 were as follows (in thousands):

	Amount		Expiration Period
Federal NOL	$	625,918	2018 - 2035
State NOL	$	202,275	2014 - 2035
Federal tax credit carryforwards	$	9,684	2018 - 2035
State tax credit carryforwards	$	9,176	Indefinite

A reconciliation of the beginning and ending amount of total gross unrecognized tax benefits is as follows (in thousands):

Balance at March 31, 2012	$	2,148
Gross decrease related to prior year tax positions		(100	)
Gross increase related to prior year tax positions		222
Gross increase related to current year tax positions		148
Lapse of statute of limitations		—

Balance at March 31, 2013	$	2,418
Gross decrease related to prior year tax positions		(93	)
Gross increase related to prior year tax positions		1
Gross increase related to current year tax positions		115
Lapse of statute of limitations		—

Balance at March 31, 2014	$	2,441
Gross increase related to prior year tax positions		11
Gross increase related to current year tax positions		112
Lapse of statute of limitations		—

Balance at March 31, 2015	$	2,564