The Company is subject to U.S. federal and various state corporate income taxes as well as taxes in foreign jurisdictions for the foreign parent and where foreign subsidiaries have been established.

For the years ended December 31, 2019, 2018 and 2017, the income (loss) before provision for income taxes consist of the following (in thousands):

	Years Ended December 31,
	2019		2018			2017
Domestic	$	9,155	$	5,966		$	5,184
Foreign		58,151		(170,394	)		(71,792	)
Total	$	67,306	$	(164,428	)	$	(66,608	)

The (provision for) benefit from income taxes consist of the following (in thousands):

	Years Ended December 31,
	2019			2018			2017
Current income taxes:
Federal	$	(423	)	$	(416	)	$	(1,533	)
State		(59	)		(131	)		(42	)
Foreign		—			0			6
Total current income taxes		(482	)		(547	)		(1,569	)
Deferred income taxes:
Federal		34			(6	)		(477	)
State		—			—			297
Foreign		—			—			—
Total deferred income taxes		34			(6	)		(180	)
Total income tax provision	$	(448	)	$	(553	)	$	(1,749	)

A reconciliation of income tax expense computed at the statutory corporate income tax rate to the effective income tax rate for the years ended December 31, 2019, 2018 and 2017 is as follows:

	Years Ended December 31,
	2019			2018			2017
Income tax expense at statutory rate		9.3	%		9.3	%		9.3	%
State income tax, net of federal benefit		(2.1	)%		0.7	%		0.3	%
Nondeductible expenses		(0.1	)%		0.0	%		0.0	%
Foreign rate differential		2.0	%		(0.4	%)		(2.5	%)
Statutory to US GAAP permanent differences		0.1	%		1.0	%		1.8	%
Stock-based compensation		(2.0	%)		1.4	%		(2.9	%)
Impact of deferred rate change		(12.2	%)		0.0	%		0.0	%
Research credits		(5.2	)%		1.8	%		0.8	%
Change in valuation allowance		10.9	%		(14.1	%)		(9.4	%)
Effective income tax rate		0.7	%		(0.3	%)		(2.6	%)

Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets are comprised of the following (in thousands):

	Years Ended December 31,
	2019			2018
Deferred tax assets:
Net operating loss carryforwards	$	31,496		$	25,418
Accruals and reserves		2,868			1,816
Operating lease liabilities		14,214			—
Deferred Rent		—			3,300
Other deferred tax assets		28			51
Stock-based compensation		5,217			2,871
Deferred revenue		(20	)		3,264
Research credit		7,150			3,322
Total deferred tax assets		60,953			40,042
Less valuation allowance		(45,913	)		(36,208	)
Net deferred tax assets		15,040			3,834
Deferred tax liabilities:
Depreciation		(3,901	)		(3,785	)
Operating lease assets		(11,068	)		—
Intangible assets		(40	)		(49	)
Other deferred tax liabilities		(20	)		(22	)
Total deferred tax liabilities		(15,029	)		(3,856	)
Long term deferred taxes	$	11		$	(22	)

The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based on the Company’s history of worldwide operating losses, the Company has concluded that it is more-likely-than-not that the benefit of its U.S. and non-U.S. deferred tax assets will not be realized. Accordingly, as of December 31, 2019 and 2018, the Company has provided a full valuation allowance against its net deferred tax assets in Switzerland, the United States and the UK for its TRACR subsidiary. The valuation allowance increased by $9.7 million during 2019, which is primarily attributable to increases in the tax rates in Switzerland as a result of tax reform beginning January 1, 2020, partially offset by 2019 taxable income.

As of December 31, 2019, the Company had available non-U.S. net operating loss carryforwards of $526.1 million of which $262.3 million relate to Switzerland, $262.3 million relate to the Canton of Zug, and $1.5 million relate to the Company’s wholly-owned subsidiary in the United Kingdom. The net operating losses generated in Switzerland and the Canton of Zug begin to expire in 2022 and the net operating losses generated in the United Kingdom can be carried forward indefinitely.

As of December 31, 2019, the Company had U.S. domestic federal research and development credit carryforwards of $4.4 million which expire in 2039 for federal purposes, which are net of uncertain tax positions of $3.0 million. As of December 31, 2019, the Company had U.S. domestic state research and development credit carryforwards of $3.4 million which begin to expire in 2034, which are net of uncertain tax positions of $2.2 million.

ASC 740 clarifies the accounting for uncertainty in income taxes recognized in an enterprise’s financial statement by prescribing the minimum recognition threshold and measurement of a tax position taken or expected to be taken in a tax return.

As of December 31, 2019, the Company had gross unrecognized tax benefits of $5.2 million of which $4.8 million would favorably impact the effective tax rate if recognized. The Company will recognize interest and penalties related to uncertain tax positions in income tax expense. As of December 31, 2019, 2018 and 2017, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statements of operations and comprehensive loss.

The aggregate changes in gross unrecognized tax benefits was as follows (in thousands):

	Years Ended December 31,
	2019		2018		2017
Balance at beginning of year	$	1,595	$	354	$	163
Increases for tax positions taken during current period		2,754		1,212		178
Increases for tax positions taken in prior periods		882		29		13
Decreases for tax positions taken during current period		—		—		—
Decreases for tax positions taken in prior periods		—		—		—
Balance at end of year	$	5,231	$	1,595	$	354

The Company files income tax returns in the U.S. federal jurisdiction, Massachusetts and certain non-U.S. jurisdictions. The Company is subject to U.S. federal, Massachusetts and non-U.S. income tax examinations by authorities for tax years ending after December 31, 2015. Research credits generated in prior tax years that are closed for examination may still be adjusted upon future examination if they have or will be used in a future period. The Company is subject to income tax examinations by authorities in its non-U.S. jurisdictions for all years.