Income Tax

The Company's effective tax rates differed from the applicable U.S. federal income tax statutory rates of 21% and 35% as a result of the following for the three months ended March 31, 2018 and 2017, respectively (dollars in thousands):



	Three months ended March 31,
	2018			2017
Tax provision at U.S. statutory rate	$	28,964		$	72,745
Increase (decrease) in income taxes resulting from:
U.S. Tax Reform provisional adjustments	775			—
Foreign tax rate differing from U.S. tax rate	1,432			(6,153		)
Differences in tax bases in foreign jurisdictions	(5,760		)	(3,383		)
Deferred tax valuation allowance	7,947			1,182
Amounts related to tax audit contingencies	835			611
Corporate rate changes	111			(1,237		)
Subpart F	658			186
Foreign tax credits	(572		)	(126		)
Global intangible low-taxed income, net of credit	4,409			—
Return to provision adjustments	—			229
Equity compensation excess benefit	(1,114		)	(1,856		)
Other, net	10			134
Total provision for income taxes	$	37,695		$	62,332
Effective tax rate	27.3		%	30.0		%

On December 22, 2017, the Tax Cuts and Jobs Act of 2017 (“U.S. Tax Reform”) was signed into law. U.S. Tax Reform 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% to 21%; (2) requiring companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries; (3) generally eliminating U.S. federal income taxes on dividends from foreign subsidiaries; (4) eliminating the corporate alternative minimum tax (“AMT”) and changing how existing AMT credits can be realized; (5) creating the base erosion anti-abuse tax (“BEAT”), a new minimum tax; (6) establishing a new provision designed to tax global intangible low-taxed income (“GILTI”), which allows for the possibility of using foreign tax credits and a deduction of up to 50 percent to offset the income tax liability (subject to some limitations); and (7) changing rules related to uses and limitations of net operating loss carryforwards created in tax years beginning after December 31, 2017.

Companies subject to GILTI have the option to account for the GILTI tax as a period cost if and when incurred, or to recognize deferred taxes for temporary differences including outside basis differences expected to reverse as GILTI. The Company has not yet made a policy election to account for GILTI, but included an estimate of the current GILTI impact in the tax provision.

As of March 31, 2018, the Company has not yet completed its accounting for the tax effects of the enactment of the U.S. Tax Reform. The Company continues to gather additional information to account for the effects of U.S. Tax Reform such as information to more precisely compute the pretax deferred tax items upon which the change in rate was applied and refine the necessary valuation allowance related to the foreign tax credits. Also, the Company also continues to monitor new regulatory and accounting guidance which could impact the provisional balances recorded as of December 31, 2017.

The effective tax rate for the three months ended March 31, 2018 was higher than the U.S. Statutory rate of 21.0% primarily as a result of income in non-U.S. jurisdictions with higher tax rates than the U.S., the inclusion of U.S. tax related to GILTI and losses in foreign jurisdictions for which the company established a valuation allowance. The higher rate was partially offset with tax benefits related to bases differences in non-U.S. jurisdictions.