Income Taxes	3 Months Ended
Mar. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The 2018 increase in income tax expense between periods of $984 million, from $430 million in 2017 to $1.41 billion in 2018, is a result of the year-over-year increase in total income before income tax expense, which is primarily due to effects of higher crude oil prices and production. The company’s effective tax rate changed between periods from 14 percent in 2017 to 28 percent in 2018. The change in effective tax rate is primarily a consequence of the mix effect resulting from the absolute level of earnings or losses and whether they arose in higher or lower tax rate jurisdictions. U.S. tax reform resulted in the remeasurement of U.S. deferred tax assets and liabilities in 2017. The final impact will be determined as the actual 2017 U.S. tax return is prepared and completed later in 2018, and this may result in a change to the provisional amounts that were recognized in 2017. Tax positions for Chevron and its subsidiaries and affiliates are subject to income tax audits by many tax jurisdictions throughout the world. For the company’s major tax jurisdictions, examinations of tax returns for certain prior tax years had not been completed as of March 31, 2018. For these jurisdictions, the latest years for which income tax examinations had been finalized were as follows: United States — 2011, Nigeria — 2000, Australia — 2006 and Kazakhstan — 2007. The company engages in ongoing discussions with tax authorities regarding the resolution of tax matters in the various jurisdictions. Both the outcomes for these tax matters and the timing of resolution and/or closure of the tax audits are highly uncertain. However, it is reasonably possible that developments regarding tax matters in certain tax jurisdictions may result in significant increases or decreases in the company’s total unrecognized tax benefits within the next 12 months. Given the number of years that still remain subject to examination and the number of matters being examined in the various tax jurisdictions, the company is unable to estimate the range of possible adjustments to the balance of unrecognized tax benefits.

Income Taxes

The 2018 increase in income tax expense between periods of $984 million, from $430 million in 2017 to $1.41 billion in 2018, is a result of the year-over-year increase in total income before income tax expense, which is primarily due to effects of higher crude oil prices and production. The company’s effective tax rate changed between periods from 14 percent in 2017 to 28 percent in 2018. The change in effective tax rate is primarily a consequence of the mix effect resulting from the absolute level of earnings or losses and whether they arose in higher or lower tax rate jurisdictions.

U.S. tax reform resulted in the remeasurement of U.S. deferred tax assets and liabilities in 2017. The final

impact will be determined as the actual 2017 U.S. tax return is prepared and completed later in 2018, and this may result in a change to the provisional amounts that were recognized in 2017.

Tax positions for Chevron and its subsidiaries and affiliates are subject to income tax audits by many tax jurisdictions throughout the world. For the company’s major tax jurisdictions, examinations of tax returns for certain prior tax years had not been completed as of March 31, 2018. For these jurisdictions, the latest years for which income tax examinations had been finalized were as follows: United States — 2011, Nigeria — 2000, Australia — 2006 and Kazakhstan — 2007.

The company engages in ongoing discussions with tax authorities regarding the resolution of tax matters in the various jurisdictions. Both the outcomes for these tax matters and the timing of resolution and/or closure of the tax audits are highly uncertain. However, it is reasonably possible that developments regarding tax matters in certain tax jurisdictions may result in significant increases or decreases in the company’s total unrecognized tax benefits within the next 12 months. Given the number of years that still remain subject to examination and the number of matters being examined in the various tax jurisdictions, the company is unable to estimate the range of possible adjustments to the balance of unrecognized tax benefits.