Income Taxes

Our tax provision or benefit from income taxes for interim periods is determined using an estimate of our annual effective tax rate, adjusted for discrete items, if any, that are taken into account in the relevant period. Each quarter we update our estimate of the annual effective tax rate, and if our estimated tax rate changes, we make a cumulative adjustment. Our quarterly tax provision and our quarterly estimate of our annual effective tax rate, are subject to significant variation due to several factors, including variability in accurately predicting our pre-tax and taxable income and loss and the mix of jurisdictions to which they relate. Additionally, our effective tax rate can be more or less volatile based on the amount of pre-tax income or loss. For example, the impact of discrete items and non-deductible expenses on our effective tax rate is greater when our pre-tax income is lower.

On December 22, 2017, the U.S. government enacted tax legislation referred to as the Tax Act. The Tax Act makes broad and complex changes to the U.S. tax code, including, but not limited to, (1) reducing the U.S. federal corporate tax rate from 35 percent to 21 percent; (2) requiring companies to pay a one-time Deemed Repatriation Transition Tax (“Transition Tax”) on certain unrepatriated earnings of foreign subsidiaries that can be paid over eight years; (3) a new provision designed to tax global intangible low-taxed income (GILTI), which allows for the possibility of using foreign tax credits (FTCs) and a deduction of up to 50 percent to offset the income tax liability (subject to some limitations); (4) the repeal of the domestic production activity deduction beginning January 1, 2018; (5) limitations on the deductibility of certain executive compensation; and (6) a new limitation on deductible interest expense beginning January 1, 2018.

The Company has not completed its accounting for the tax effects of enactment of the Tax Act. However, the Company has made a reasonable estimate of the effects on its existing deferred tax balances and the one-time Transition Tax. In other cases, the Company has not been able to make a reasonable estimate and continues to account for those items based on its existing accounting under ASC 740 ("Income Taxes"), and the provisions of the tax laws that were in effect immediately prior to enactment.

The SEC staff issued Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act ("SAB 118"), which provides guidance on accounting for the tax effects of the Tax Act. SAB 118 provides a measurement period that should not extend beyond one year from the Tax Act enactment date for companies to complete the accounting under ASC 740. In accordance with SAB 118, a company must reflect the income tax effects of those aspects of the Act for which the accounting under ASC 740 is complete. To the extent that a company’s accounting for certain income tax effects of the Tax Act is incomplete but it is able to determine a reasonable estimate, it must record a provisional estimate in the financial statements. If a company cannot determine a provisional estimate to be included in the financial statements, it should continue to apply ASC 740 on the basis of the provisions of the tax laws that were in effect immediately before the enactment of the Tax Act.

For those items for which it was able to determine a reasonable estimate, the Company recognized a provisional net tax benefit of $128.2 million during 2017. This net benefit primarily consists of a net benefit for the corporate rate reduction on the deferred tax assets and liabilities of $210 million and a net expense for the Transition Tax of $81.8 million.

While the Company was able to make a reasonable estimate of the impact of the reduction in corporate rate on its net deferred tax liabilities, the impact may be affected by other analysis related to the Tax Act, including, but not limited to, the Company’s calculation of deemed repatriation of deferred foreign income. The Company was also not able to make a reasonable estimate of the impact of state taxes on adjustments made to federal temporary differences as a result of the Tax Act, or the impact of the new limitations on the deductibility of certain executive compensation. As a result, the Company continues to account for the impact of state taxes on adjustments made to federal temporary differences and the deductibility of certain executive compensation based on its existing accounting under ASC 740 and the provisions of the tax laws that were in effect immediately prior to enactment.

In all cases, the Company will continue to make and refine its calculations as additional analysis is completed. We did not make any adjustments to these provisional amounts during the three months ended March 31, 2018. We are continuing to gather additional information to complete our accounting for these items and expect to complete our accounting within the measurement period.

The provision for income taxes differs from amounts computed by applying the U.S. federal tax rate of 21% for 2018 and 35% for 2017 to income before income taxes for the three months ended March 31, 2018 and 2017 due to the following (in thousands):



	2018					2017
Computed tax expense at the U.S. federal tax rate	$	48,157		21.0	%	$	58,579		35.0	%
Changes resulting from:
Foreign income tax differential	2,016			0.9	%	(5,843		)	(3.5	)%
Excess tax benefits related to stock-based compensation	(4,624		)	(2.0	)%	(8,721		)	(5.2	)%
State taxes net of federal benefits	3,373			1.5	%	1,607			1.0	%
Foreign-sourced nontaxable income	(6,588		)	(2.9	)%	(3,372		)	(2.0	)%
Foreign withholding taxes	5,471			2.4	%	2,045			1.2	%
GILTI Tax, net of foreign tax credits	4,921			2.1	%	—			—	%
Other	1,656			0.7	%	(620		)	(0.4	)%
Provision for income taxes	$	54,382		23.7	%	$	43,675		26.1	%