The provision for income taxes is determined using the asset and liability approach of accounting for income taxes. Under this approach, deferred taxes represent the estimated future tax effects of temporary differences between book and tax treatment of assets and liabilities and carryforwards to the extent they are realizable. We record a valuation allowance to reduce our deferred tax assets to the amount that is more likely than not to be realized. While we consider future taxable income and ongoing prudent and feasible tax planning strategies in assessing the need for a valuation allowance, in the event we determine that we would be able to realize our deferred tax assets in the future in excess of the net recorded amount, a reduction of the valuation allowance would increase income in the period such determination was made. Likewise, should we determine that we would not be able to realize all or part of our net deferred tax asset in the future, a reduction to the deferred tax asset would be charged to income in the period such determination was made.

We record a liability for uncertain tax positions that do not meet the more likely than not standard as prescribed by the authoritative guidance for income tax accounting. We record tax benefits for only those positions that we believe will more likely than not be sustained. Unrecognized tax benefits are the differences between tax positions taken, or expected to be taken, in tax returns, and the benefits recognized for accounting purposes. We classify uncertain tax positions as long-term liabilities.

Significant judgment is required in determining our worldwide provision for income taxes and our income tax filings are regularly under audit by tax authorities. Any audit result differing from amounts recorded would increase or decrease income in the period that we determine such adjustment is likely. Interest expense and penalties associated with the underpayment of income taxes are included in income tax expense.

The 2017 Tax Act was enacted on December 22, 2017, and includes significant changes to the U.S. corporate tax system. Effective January 1, 2018, the 2017 Tax Act reduced the U.S. federal corporate tax rate from 35% to 21%, transitioned the U.S. federal tax system from a worldwide tax system to a territorial tax system, and eliminated or reduced certain domestic deductions among other changes. In converting to the new territorial tax system, a deemed repatriation tax on previously tax-deferred earnings of certain foreign subsidiaries was required to be recognized as of December 31, 2017, and is payable over eight years.



(in thousands)	For the Years Ended December 31,
	2019		2018			2017
Current
Federal	$	52,194	$	47,130		$	92,453
State	11,967		10,415			9,258
International	24,239		22,015			23,993
	88,400		79,560			125,704
Deferred
Federal	4,826		3,970			(1,201		)
State	269		(937		)	(4,102		)
International	931		(1,898		)	(2,613		)
	6,026		1,135			(7,916		)
	$	94,426	$	80,695		$	117,788



	For the Years Ended December 31,
	2019		2018		2017

U.S. federal statutory rate	21.0	%	21.0	%	35.0	%
State income tax, net of federal tax benefit	2.3		2.6		1.9
Taxation on international earnings	(1.1	)	(0.8	)	(5.5	)
Foreign derived intangible income	(1.1	)	(1.3	)	—
Share-based compensation from settlements	(3.6	)	(4.7	)	(7.3	)
Domestic manufacturing exclusions	—		—		(1.1	)
Research and development credit	(0.8	)	(0.9	)	(0.9	)
Impact of the 2017 Tax Act	—		0.5		9.4
State income tax carryforwards	—		(0.2	)	(1.4	)
Other, net	1.4		1.4		0.8
Effective tax rate	18.1	%	17.6	%	30.9	%

Our effective income tax rate was 18.1% for the year ended December 31, 2019, and 17.6% for the year ended December 31, 2018. Our effective income tax rate for the year ended December 31, 2019 was higher primarily due to lower tax benefits related to share-based compensation, partially offset by a nonrecurring item recorded in the first quarter of 2018, that resulted from the 2017 Tax Cut and Jobs Act.

Our effective income tax rate was 17.6% for the year ended December 31, 2018, and 30.9% for the year ended December 31, 2017. Our effective income tax rate for the year ended December 31, 2018, was lower primarily related to the reduction in the 2018 U.S. statutory tax rate to 21% from 35%, as well as the comparison to a nonrecurring charge resulting from the 2017 Tax Act for the year ended December 31, 2017. These favorable impacts were offset by lower tax benefits related to share-based compensation and the prior year utilization of foreign tax credits.

We have received a tax ruling from the Netherlands that documents our mutual understanding of how existing tax laws apply to our circumstances. This ruling expires as of December 31, 2022, and we have been informed that it will not be renewed due to changes to the advance ruling policy in the Netherlands. While the absence of an advance agreement does not preclude our ability to continue to apply existing tax laws in the same manner as allowed by the existing ruling, the lack of such agreement could create uncertainty as to our future tax rate. Primarily as a result of this tax ruling, our net income was higher by $13.7 million, $9.2 million, and $8.9 million for the years ended December 31, 2019, 2018, and 2017, respectively. The benefit from these tax rulings is reflected within the overall benefit received from international income taxes in the table above.



(in thousands)	December 31, 2019			December 31, 2018

Assets
Accrued expenses	$	25,296		$	22,652
Accounts receivable reserves	617			776
Deferred revenue	6,073			7,637
Inventory basis differences	3,315			2,787
Property-based differences	3,113			1,652
Share-based compensation	10,593			9,267
Other	1,160			2,314
Net operating loss carryforwards	4,045			3,208
Tax credit carryforwards	12,276			10,226
Unrealized losses on foreign currency exchange contracts and investments	20			404
Total assets	66,508			60,923
Valuation allowance	(9,454		)	(6,212		)
Total assets, net of valuation allowance	57,054			54,711

Liabilities
Customer acquisition costs	(28,519		)	(24,323		)
Property-based differences	(33,802		)	(32,494		)
Intangible asset basis differences	(14,513		)	(13,454		)
Other	(3,961		)	(3,319		)
Unrealized gains on foreign currency exchange contracts and investments	(1,183		)	(1,907		)
Total liabilities	(81,978		)	(75,497		)
Net deferred tax assets (liabilities)	$	(24,924	)	$	(20,786	)

As of December 31, 2019, we have recorded a valuation allowance of $9.5 million against certain deferred tax assets related to temporary differences including net operating loss (“NOL”) and tax credit carryforwards, as it is more likely than not that they will not be realized or utilized within the carryforward period.

As of December 31, 2019, we have NOL’s in certain state and international jurisdictions of approximately $17.0 million available to offset future taxable income. Most of these NOL’s will expire at various dates between 2021 and 2026 and the remainder have indefinite lives.



(in thousands)	For the Years Ended December 31,
	2019			2018			2017

Total amounts of unrecognized tax benefits, beginning of period	$	24,247		$	21,417		$	18,463
Gross (decreases) increases in unrecognized tax positions as a result of tax positions taken during a prior period	(276		)	2,991			74
Gross increases in unrecognized tax positions as a result of tax positions taken in the current period	4,083			461			4,681
Decreases in unrecognized tax positions relating to settlements with taxing authorities	—			—			(713		)
Decreases in unrecognized tax positions as a result of a lapse of the applicable statutes of limitations	(1,213		)	(622		)	(1,088		)
Total amounts of unrecognized tax benefits, end of period	$	26,841		$	24,247		$	21,417

The total amount of unrecognized tax benefits at December 31, 2019 and December 31, 2018, was $26.8 million and $24.2 million, respectively. Of the total unrecognized tax benefits at December 31, 2019 and 2018, $21.2 million and $18.3 million, respectively, comprise unrecognized tax positions that would, if recognized, affect our effective tax rate.

During the years ended December 31, 2019, 2018 and 2017, we recorded interest expense and penalties of $1.8 million, $1.2 million, and $0.9 million, respectively, as income tax expense in our consolidated statement of income. At December 31, 2019 and 2018, we had $3.6 million and $2.1 million, respectively, of estimated interest expense and penalties accrued in our consolidated balance sheets.

In the ordinary course of our business, our income tax filings are regularly under audit by tax authorities. While we believe we have appropriately provided for all uncertain tax positions, amounts asserted by taxing authorities could be greater or less than our accrued position. Accordingly, additional provisions on income tax matters, or reductions of previously accrued provisions, could be recorded in the future as we revise our estimates due to changing facts and circumstances or the underlying matters are settled or otherwise resolved. We are currently under tax examinations in various jurisdictions. We anticipate that these examinations will be concluded within the next two years. With few exceptions, we are no longer subject to income tax examinations in any jurisdiction in which we conduct significant taxable activities for years before 2014.