14 Income taxes

a. Income tax benefit / (expense)

No current tax charges or liabilities were recorded in 2016, 2015 and 2014 by the Dutch and U.S operation since these operations were in a loss-making position. Due to the uncertainty surrounding the realization of the favorable tax attributes in future tax returns, the Company has recorded a full valuation allowance against the Company's otherwise recognizable net deferred tax assets.

For the years ended December 31, 2016, 2015 and 2014, loss before income taxes consists of the following:

	Years ended December 31,
	2016			2015			2014
	in thousands
Dutch operations	$	(51,107	)	$	(63,304	)	$	(41,063	)
U.S. operations		(21,221	)		(20,406	)		(8,937	)
Foreign operations		99			448			(312	)

Total	$	(72,229	)	$	(83,262	)	$	(50,312	)

The income tax benefit / (expense) for the years ended December 31, 2016, 2015 and 2014, consists of the following:

	Years ended December 31,
	2016			2015			2014
	in thousands
Current benefit / (expense)
Dutch operations	$	—		$	—		$	—
U.S. operations		—			—			—
Foreign operations		(51	)		(51	)		—
Deferred benefit / (expense)
Dutch operations		(1,094	)		714			535
U.S. operations		—			—			—
Foreign operations		—			516			—

Total income tax benefit / (expense)	$	(1,145	)	$	1,179		$	535

b. Tax rate reconciliation

The reconciliation of the Dutch statutory income tax rate to the Company's effective tax rate for the years ended December 31, 2016, 2015 and 2014, is as follows:

	December 31, 2016			December 31, 2015			December 31, 2014
	in thousands
Net loss before tax for the period	$	(72,229	)	$	(83,262	)	$	(50,312	)
Expected tax benefit / (expense) at the tax rate enacted in the Netherlands (25%)		18,057			20,816			12,578
Difference in tax rates between the Netherlands and foreign countries		1,905			1,816			819
Net change in valuation allowance		(20,054	)		(16,301	)		(10,843	)
Non deductible expenses		(1,323	)		(4,984	)		(2,111	)
Deductible expenses directly recognized in equity		—			168			139
Change in fair value of contingent consideration		270			(336	)		(47	)

Income tax benefit / (expense)	$	(1,145	)	$	1,179		$	535

Non-deductible expenses predominantly relate to share-based compensation expenses for an amount of $1.6 million in 2016 (2015: $2.9 million; 2014: $2.1 million) and non-deductible results on derivative financial instruments of nil (2015: $1.9 million; 2014: nil).

c. Significant components of deferred taxes

The tax effects of temporary differences that give rise to significant portions of deferred tax assets and deferred tax liabilities at December 31, 2016 and 2015 are as follows:

	December 31, 2016			December 31, 2015
				in thousands
Deferred tax assets:
Net operating loss carryforwards	$	59,468		$	40,236
Intangible assets		1,621			1,986
Property, plant and equipment		1,412			1,202
Deferred revenue		19,997			21,410
Accrued revenue		—			962
Accrued expenses and other current liabilities		144			935

Gross deferred tax asset	$	82,642		$	66,731
Less valuation allowance		(82,642	)		(65,593	)

Net deferred tax asset		—			1,138
Deferred tax liabilities:
Intangible assets		—			—
Long-term loan to foreign operation		—			(1,138	)

Net deferred tax liability	$	—		$	(1,138	)

Net deferred tax asset/(liability)	$	—		$	—

The valuation allowance for deferred tax assets as of December 31, 2016, 2015 and 2014 was $82.6 million, $65.6 million and $50.0 million, respectively. The net change in the total valuation allowance was an increase of $17.0 million in 2016 and an increase of $15.6 million in 2015. The valuation allowance at December 31, 2016 was primarily related to net operating loss carryforwards that, in the judgment of management, are not more-likely than-not to be realized. Management considers the scheduled reversal of deferred tax liabilities (including the impact of available carryback and carryforward periods), projected future taxable income and tax-planning strategies in making this assessment.

According to Dutch income tax law, a tax loss carry-forward expires nine years after the end of the respective period.

The Dutch fiscal unity has as of December 31, 2016 an estimated $182.0 million (2015: $137.0 million; 2014: $175.7 million) of taxable losses that can be offset in the following nine years. The expiration dates of these Dutch losses, is summarized in the following table. In the years ended December 31, 2016 and 2015, no amounts of unused tax losses expired.

	2017		2018		2019		2020		2021
	in thousands
Loss expiring	$	21,523		17,579		19,070		17,333		13,043

There are no unrecognized tax benefits for the years ended December 31, 2016, 2015 and 2014.