	For Years Ended December 31,
	2018		2017		2016
U.S.	$	5,672	$	5,130	$	3,953
Non-U.S.		1,014		950		977
Total	$	6,686	$	6,080	$	4,930

	For Years Ended December 31,
	2018							2017						2016
	Current		Deferred			Total		Current		Deferred		Total		Current		Deferred			Total
U.S. federal	$	979	$	(98	)	$	881	$	2,101	$	51	$	2,152	$	1,289	$	(122	)	$	1,167
Non-U.S.		225		(8	)		217		173		61		234		238		(80	)		158
U.S. state		7		1			8		12		—		12		10		—			10
Total	$	1,211	$	(105	)	$	1,106	$	2,286	$	112	$	2,398	$	1,537	$	(202	)	$	1,335

Principal reconciling items from the U.S. statutory income tax rate to the effective tax rate (provision for income taxes as a percentage of income before income taxes) are as follows:

	For Years Ended December 31,
	2018			2017			2016
U.S. statutory income tax rate		21.0	%		35.0	%		35.0	%
U.S. tax benefit for foreign derived intangible income		(5.3	)		—			—
U.S. Tax Act transitional non-cash expense		4.2			—			—
U.S. Tax Act enactment-date effects and measurement period adjustments		(0.7	)		12.7			—
U.S. tax on global intangible low-taxed income		0.4			—			—
U.S. tax benefit for manufacturing		—			(1.6	)		(1.5	)
U.S. excess tax benefit for stock compensation		(2.0	)		(4.1	)		(3.0	)
U.S. R&D tax credit		(1.3	)		(1.1	)		(1.2	)
U.S. non-deductible expenses		0.2			0.2			0.3
Non-U.S. effective tax rates		0.1			(2.5	)		(3.7	)
Impact of changes to uncertain tax positions		—			0.7			0.6
Other		(0.1	)		0.1			0.6
Effective tax rate		16.5	%		39.4	%		27.1	%

The Tax Act was enacted on December 22, 2017. The Tax Act reduces the U.S. statutory income tax rate from 35 percent to 21 percent and requires companies to pay a one-time tax on indefinitely reinvested earnings of certain non-U.S. subsidiaries that were previously tax deferred. We applied the guidance in Staff Accounting Bulletin No. 118 when accounting for the enactment-date effects of the Tax Act in 2017 and throughout 2018. As of December 31, 2017, we had not completed our accounting for the enactment-date income tax effects of the Tax Act for the following aspects: one-time tax on indefinitely reinvested earnings and the effects on our existing deferred tax balances. As of December 31, 2018, we completed our accounting for the enactment-date income tax effects of the Tax Act. We booked a provisional amount of $773 million in 2017 and reduced our provisional amount by $44 million in 2018, for a net of $729 million. The Tax Act also included the global intangible low-taxed income (GILTI) tax for years beginning in 2018. We account for the effects of GILTI as a component of income tax expense in the period in which the tax arises.

The earnings represented by non-cash operating assets, such as fixed assets and certain inventory, will continue to be permanently reinvested outside the United States. The tax on indefinitely reinvested earnings eliminates any additional U.S. taxation of these earnings upon repatriation to the United States. Consequently, no U.S. tax provision has been made for the future remittance of these earnings. However, withholding taxes in certain non-U.S. jurisdictions will be incurred upon repatriation of available cash to the United States. A provision has been made for deferred taxes on these undistributed earnings to the extent that dividend payments from these subsidiaries are expected to result in a withholding tax liability. As of December 31, 2018, we have no basis differences that would result in material unrecognized deferred tax liabilities.

Our effective tax rate is affected by U.S. tax benefits and tax rates applicable to our operations in many of the jurisdictions in which we operate, most of which were lower than the U.S. statutory income tax rate prior to enactment of the Tax Act. These non-U.S. tax rates are generally statutory in nature and without expiration.

	December 31,
	2018			2017
Deferred tax assets:
Deferred loss and tax credit carryforwards	$	247		$	256
Accrued expenses		129			119
Stock compensation		122			107
Inventories and related reserves		107			93
Retirement costs for defined benefit and retiree health care		80			38
Other		—			9
Total deferred tax assets, before valuation allowance		685			622
Valuation allowance		(172	)		(165	)
Total deferred tax assets, after valuation allowance		513			457
Deferred tax liabilities:
Acquisition-related intangibles and fair-value adjustments		(142	)		(207	)
International earnings		(43	)		(64	)
Other		(75	)		—
Total deferred tax liabilities		(260	)		(271	)
Net deferred tax asset	$	253		$	186

The deferred tax assets and liabilities based on tax jurisdictions are presented on our Consolidated Balance Sheets as follows:

We make an ongoing assessment regarding the realization of U.S. and non-U.S. deferred tax assets. This assessment is based on our evaluation of relevant criteria, including the existence of deferred tax liabilities that can be used to absorb deferred tax assets, taxable income in prior carryback years and expectations for future taxable income. Valuation allowances increased by $7 million and $37 million in 2018 and 2017, respectively. These changes had no impact to net income in 2018 or 2017.

We have U.S. and non-U.S. tax loss carryforwards of approximately $6 million, none of which will expire before the year 2028.

Cash payments made for income taxes, net of refunds, were $705 million, $1.80 billion and $1.15 billion in 2018, 2017 and 2016, respectively.

We operate in a number of tax jurisdictions, and our income tax returns are subject to examination by tax authorities in those jurisdictions who may challenge any item on these tax returns. Because the matters challenged by authorities are typically complex, their ultimate outcome is uncertain. Before any benefit can be recorded in our financial statements, we must determine that it is “more likely than not” that a tax position will be sustained by the appropriate tax authorities. We recognize accrued interest related to uncertain tax positions and penalties as components of OI&E.

	2018			2017			2016
Balance, January 1	$	300		$	243		$	84
Additions based on tax positions related to the current year		3			17			4
Additions for tax positions of prior years		1			42			189
Reductions for tax positions of prior years		—			(1	)		(2	)
Settlements with tax authorities		(18	)		(1	)		(32	)
Balance, December 31	$	286		$	300		$	243

Interest income (expense) recognized in the year ended December 31	$	(15	)	$	(19	)	$	4

Interest receivable (payable) as of December 31	$	(49	)	$	(38	)	$	13

The liability for uncertain tax positions is a component of other long-term liabilities on our Consolidated Balance Sheets.

All of the $286 million and $300 million liabilities for uncertain tax positions as of December 31, 2018 and 2017, respectively, are comprised of positions that, if recognized, would lower the effective tax rate. If these liabilities are ultimately realized, $30 million and $13 million of existing deferred tax assets in 2018 and 2017, respectively, would also be realized. It is reasonably possible that the $286 million liability as of December 31, 2018, could decrease by up to $223 million in 2019 for the resolution of a tax depreciation-related position.

As of December 31, 2018, the statute of limitations remains open for U.S. federal tax returns for 2013 and following years. Audit activities related to our U.S. federal tax returns through 2012 have been completed except for certain pending tax treaty procedures for relief from double taxation. The procedures for relief from double taxation pertain to U.S. federal tax returns for the years 2006 through 2012. The audit of the U.S. federal tax returns for 2013 through 2015 is underway.

In non-U.S. jurisdictions, the years open to audit represent the years still open under the statute of limitations. With respect to major jurisdictions outside the United States, our subsidiaries are no longer subject to income tax audits for years before 2007.