Income Taxes

The following table compares our income tax expense and effective tax rates for the three and six months ended September 30, 2017 and 2016:



	Three months ended						Six months ended
	September 30,						September 30,
(Dollars in thousands)	2017			2016			2017			2016
Income tax expense	$	105		$	82		$	183		$	124
Effective tax rate	(3.3		)%	(3.5		)%	(3.0		)%	(2.7		)%

For the three and six months ended September 30, 2017, the effective tax rate was different than the statutory rate due primarily to the recognition of net operating losses as deferred tax assets, which were offset by increases in the valuation allowance, certain foreign and state tax effects, and other U.S. permanent book to tax differences.

For the three and six months ended September 30, 2016, the effective tax rate was different than the statutory rate due primarily to the recognition of net operating losses as deferred tax assets, which were offset by increases in the valuation allowance, certain foreign and state tax effects, and other U.S. permanent book to tax differences.

We have recorded a valuation allowance offsetting substantially all of our deferred tax assets. The ultimate realization of deferred tax assets depends on the generation of future taxable income during the periods in which those temporary differences are deductible. Because of our losses in prior periods, management believes that it is more-likely-than-not that we will not realize the benefits of these deductible differences.