Income taxes (Tables)

12 Months Ended

Dec. 31, 2021

Income taxes

Schedule of losses before income taxes

For financial reporting purposes, losses before income taxes for the years ended December 31, 2021, 2020 and 2019 consisted of the following (in thousands):

	Year ended December 31,
	2021		2020		2019
United States	$	(11,403)	$	(11,603)	$	(7,886)
Foreign (Austria)		(64,261)		(32,479)		(35,151)
Net loss before tax	$	(75,664)	$	(44,082)	$	(43,037)

Schedule of effective income tax rate reconciliation

	Year ended December 31,
	2021			2020			2019
U.S. federal statutory income tax rate		(21.0)	%		(21.0)	%		(21.0)	%
State income taxes, net of federal benefit		—			—			—
Foreign tax rate differential(1)		(4.0)			(4.0)			(4.0)
Not taxable government grants(2)		(3.8)			(4.7)			(5.4)
Stock-based compensation(3)		(1.5)			(1.0)			(0.3)
Other		0.1			0.5			(0.3)
Change in deferred tax asset valuation allowance(4)		30.2			30.2			31.0
Effective income tax rate		—	%		—	%		—	%

⁽¹⁾ The 4% increase for the years ended December 31, 2021, 2020 and 2019, respectively, resulted from tax rate differences between U.S. and non-U.S. jurisdictions. Net loss before tax was principally generated in Austria, where the statutory tax rate is 25%.

⁽²⁾ For the years ended December 31, 2021, 2020 and 2019, 3.8%, 4.7% and 5.4% increase, respectively, resulted from non-taxable research subsidies received from Austrian government agencies.

⁽³⁾ For the years ended December 31, 2021, 2020 and 2019, 1.5%, 1.0% and 0.3% increase, respectively, resulted from non-taxable Stock-based compensation expense.

⁽⁴⁾ For the years ended December 31, 2021, 2020 and 2019, 30.2% reduction, 30.2% reduction and 31.0% reduction, respectively, resulted from changes in valuation allowance on deferred tax assets. Deferred tax assets will only be recovered when the generation of future taxable income is more likely than not. Due to the nature of the Company's research activities and the inherent uncertainties the deferred tax assets have been fully impaired.

Components of the net deferred tax assets or liabilities

Components of the net deferred tax assets or liabilities as of the years ended December 31, 2021 and 2020 consisted of the following (in thousands):

	Year ended December 31,
	2021		2020
Deferred tax assets:
Net operating loss carryforwards	$	55,752	$	43,563
Credit carryforwards		64		64
Accrued expenses and other		357		(36)
Stock-based compensation		1,209		2,725
Operating lease liabilities		1,378		1,513
Finance lease liabilities		5		103
Total deferred tax assets		58,765		47,932
Valuation allowance		(53,728)		(46,064)
Total deferred tax assets		5,037		1,868
Deferred tax liabilities:
Accrued expenses and other		(3,604)		—
Fixed assets and intangible assets		(11)		—
Operating lease right of use asset		(1,400)		(1,614)
Finance lease right of use asset		(22)		(254)
Total deferred tax liabilities		(5,037)		(1,868)
Net deferred tax assets	$	—	$	—

Changes in the valuation allowance for deferred tax assets

Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2021, 2020 and 2019 related primarily to the increases in net operating loss carryforwards as follows (in thousands):

	Year ended December 31,
	2021		2020		2019
Valuation allowance at beginning of period	$	(46,064)	$	(32,583)	$	(19,156)
Increases		(7,664)		(13,481)		(13,427)
Valuation allowance at end of period	$	(53,728)	$	(46,064)	$	(32,583)