Income Taxes	9 Months Ended
Sep. 30, 2018
Income Taxes
Income Taxes	Note 10—Income Taxes Tax provision and rate—Transocean Ltd., a holding company and Swiss resident, is exempt from cantonal and communal income tax in Switzerland, but is subject to Swiss federal income tax. Our provision for income taxes is based on the tax laws and rates applicable in the jurisdictions in which we operate and earn income. In the nine months ended September 30, 2018 and 2017, our estimated effective tax rate, excluding discrete items, was (15.6) percent and 64.2 percent, respectively, based on estimated annual income or loss before income taxes. In the nine months ended September 30, 2018, compared to the nine months ended September 30, 2017, our effective tax rate decreased primarily due to changes in the relative blend of income from operations in certain jurisdictions and the loss before income taxes and the increased tax expense as a result of the U.S. base erosion and anti‑abuse tax (“BEAT”). We consider the tax effect, if any, of the excluded items noted, as well as settlements of prior year tax estimates to be discrete period tax expenses or benefits. In the nine months ended September 30, 2018 and 2017, the effect of the various discrete period tax items was a net tax expense of $91 million and a net tax benefit of $57 million, respectively. In the nine months ended September 30, 2018, such discrete items were primarily related to the U. S. transition tax on non‑U.S. earnings. In the nine months ended September 30, 2017, such discrete items were largely related to the tax benefit of changes in unrecognized tax benefits associated with tax positions taken in prior years, valuation allowances on deferred tax assets for foreign tax credits not expected to be realized and deductions related to resolution of certain litigation matters related to the Macondo well incident. For the nine months ended September 30, 2018 and 2017, these discrete tax items, coupled with the excluded income and expense items noted above, resulted in an effective tax rate of (7.2) percent and (3.6) percent, respectively, based on income or loss before income tax expense. During the three months ended September 30, 2018, our U.S. valuation allowance increased by $91 million due to the deferred tax benefit recognized from the impairment of GSF C.R. Luigs. U.S. tax reform—In December 2017, the U.S. enacted the 2017 Tax Act, which included prospective changes beginning in 2018, including a BEAT, a global intangible low‑taxed income (“GILTI”) tax, additional limitations on the deductibility of executive compensation, limitations on the deductibility of interest and repeal of the domestic manufacturing deduction. Effective January 1, 2018, we elected to treat any potential GILTI inclusions as a period cost, and we have also evaluated our bareboat charter structure and have concluded that the current structure of our U.S. operations is subject to BEAT. We have reflected the estimated impact of this tax in our provision for the nine months ended September 30, 2018. A significant portion of our BEAT liability is contractually protected due to a change in law provision in certain drilling contracts. Transition tax on non‑U.S. earnings—The 2017 Tax Act imposes a one‑time transition tax on certain unremitted earnings and profits of our non‑U.S. subsidiaries. At December 31, 2017, we did not have the necessary information available, prepared and analyzed to develop a reasonable estimate of the transition tax. In the nine months ended September 30, 2018, we recorded income tax expense of $104 million for estimated transition taxes and an income tax benefit of $17 million for the estimated effect on the utilization of foreign tax credits. Due to the number of years and complexity of determining amounts and composition of earnings and profits held in cash and other assets by the non‑U.S. subsidiaries of our U.S. subsidiaries subject to the transition tax, the determination of the transition tax requires further analysis. The ultimate effect of our analysis may result in changes to our current estimate. We have not yet made any changes to our assertion that the unremitted earnings of our non‑U.S. subsidiaries will be indefinitely reinvested. We will complete our evaluation within the measurement period provided by Staff Accounting Bulletin No. 118. Tax returns—We file federal and local tax returns in several jurisdictions throughout the world. With few exceptions, we are no longer subject to examinations of our U.S. and non‑U.S. tax matters for years prior to 2010. Our tax returns in the major jurisdictions in which we operate, other than Brazil, as mentioned below, are generally subject to examination for periods ranging from three to six years. We have agreed to extensions beyond the statute of limitations in two major jurisdictions for up to 20 years. Tax authorities in certain jurisdictions are examining our tax returns and in some cases have issued assessments. We are defending our tax positions in those jurisdictions. While we cannot predict or provide assurance as to the timing or the outcome of these proceedings, we do not expect the ultimate liability to have a material adverse effect on our condensed consolidated statement of financial position or results of operations, although it may have a material adverse effect on our condensed consolidated statement of cash flows. Brazil tax investigations—In December 2005, the Brazilian tax authorities began issuing tax assessments with respect to our tax returns for the years 2000 through 2004. In January 2008, we filed a protest letter with the Brazilian tax authorities for these tax assessments, and we are currently engaged in the appeals process. In May 2014, the Brazilian tax authorities issued an additional tax assessment for tax years 2009 and 2010, and in June 2014, we filed protests with the Brazilian tax authorities for these tax assessments. In September 2018, a portion of one of the cases was favorably closed. As of September 30, 2018, the remaining aggregate tax assessment was for BRL 946 million, equivalent to $234 million, including penalties and interest. We believe our returns are materially correct as filed, and we are vigorously contesting these assessments. An unfavorable outcome on these proposed assessments could result in a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Other tax matters—We conduct operations through our various subsidiaries in countries throughout the world. Each country has its own tax regimes with varying nominal rates, deductions and tax attributes. From time to time, we may identify changes to previously evaluated tax positions that could result in adjustments to our recorded assets and liabilities. Although we are unable to predict the outcome of these changes, we do not expect the effect, if any, resulting from these adjustments to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Note 10—Income Taxes

Tax provision and rate—Transocean Ltd., a holding company and Swiss resident, is exempt from cantonal and communal income tax in Switzerland, but is subject to Swiss federal income tax. Our provision for income taxes is based on the tax laws and rates applicable in the jurisdictions in which we operate and earn income. In the nine months ended September 30, 2018 and 2017, our estimated effective tax rate, excluding discrete items, was (15.6) percent and 64.2 percent, respectively, based on estimated annual income or loss before income taxes. In the nine months ended September 30, 2018, compared to the nine months ended September 30, 2017, our effective tax rate decreased primarily due to changes in the relative blend of income from operations in certain jurisdictions and the loss before income taxes and the increased tax expense as a result of the U.S. base erosion and anti‑abuse tax (“BEAT”).

We consider the tax effect, if any, of the excluded items noted, as well as settlements of prior year tax estimates to be discrete period tax expenses or benefits. In the nine months ended September 30, 2018 and 2017, the effect of the various discrete period tax items was a net tax expense of $91 million and a net tax benefit of $57 million, respectively. In the nine months ended September 30, 2018, such discrete items were primarily related to the U. S. transition tax on non‑U.S. earnings. In the nine months ended September 30, 2017, such discrete items were largely related to the tax benefit of changes in unrecognized tax benefits associated with tax positions taken in prior years, valuation allowances on deferred tax assets for foreign tax credits not expected to be realized and deductions related to resolution of certain litigation matters related to the Macondo well incident. For the nine months ended September 30, 2018 and 2017, these discrete tax items, coupled with the excluded income and expense items noted above, resulted in an effective tax rate of (7.2) percent and (3.6) percent, respectively, based on income or loss before income tax expense. During the three months ended September 30, 2018, our U.S. valuation allowance increased by $91 million due to the deferred tax benefit recognized from the impairment of GSF C.R. Luigs.

U.S. tax reform—In December 2017, the U.S. enacted the 2017 Tax Act, which included prospective changes beginning in 2018, including a BEAT, a global intangible low‑taxed income (“GILTI”) tax, additional limitations on the deductibility of executive compensation, limitations on the deductibility of interest and repeal of the domestic manufacturing deduction. Effective January 1, 2018, we elected to treat any potential GILTI inclusions as a period cost, and we have also evaluated our bareboat charter structure and have concluded that the current structure of our U.S. operations is subject to BEAT. We have reflected the estimated impact of this tax in our provision for the nine months ended September 30, 2018. A significant portion of our BEAT liability is contractually protected due to a change in law provision in certain drilling contracts.

Transition tax on non‑U.S. earnings—The 2017 Tax Act imposes a one‑time transition tax on certain unremitted earnings and profits of our non‑U.S. subsidiaries. At December 31, 2017, we did not have the necessary information available, prepared and analyzed to develop a reasonable estimate of the transition tax. In the nine months ended September 30, 2018, we recorded income tax expense of $104 million for estimated transition taxes and an income tax benefit of $17 million for the estimated effect on the utilization of foreign tax credits. Due to the number of years and complexity of determining amounts and composition of earnings and profits held in cash and other assets by the non‑U.S. subsidiaries of our U.S. subsidiaries subject to the transition tax, the determination of the transition tax requires further analysis. The ultimate effect of our analysis may result in changes to our current estimate. We have not yet made any changes to our assertion that the unremitted earnings of our non‑U.S. subsidiaries will be indefinitely reinvested. We will complete our evaluation within the measurement period provided by Staff Accounting Bulletin No. 118.

Tax returns—We file federal and local tax returns in several jurisdictions throughout the world. With few exceptions, we are no longer subject to examinations of our U.S. and non‑U.S. tax matters for years prior to 2010. Our tax returns in the major jurisdictions in which we operate, other than Brazil, as mentioned below, are generally subject to examination for periods ranging from three to six years. We have agreed to extensions beyond the statute of limitations in two major jurisdictions for up to 20 years. Tax authorities in certain jurisdictions are examining our tax returns and in some cases have issued assessments. We are defending our tax positions in those jurisdictions. While we cannot predict or provide assurance as to the timing or the outcome of these proceedings, we do not expect the ultimate liability to have a material adverse effect on our condensed consolidated statement of financial position or results of operations, although it may have a material adverse effect on our condensed consolidated statement of cash flows.

Brazil tax investigations—In December 2005, the Brazilian tax authorities began issuing tax assessments with respect to our tax returns for the years 2000 through 2004. In January 2008, we filed a protest letter with the Brazilian tax authorities for these tax assessments, and we are currently engaged in the appeals process. In May 2014, the Brazilian tax authorities issued an additional tax assessment for tax years 2009 and 2010, and in June 2014, we filed protests with the Brazilian tax authorities for these tax assessments. In September 2018, a portion of one of the cases was favorably closed. As of September 30, 2018, the remaining aggregate tax assessment was for BRL 946 million, equivalent to $234 million, including penalties and interest. We believe our returns are materially correct as filed, and we are vigorously contesting these assessments. An unfavorable outcome on these proposed assessments could result in a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Other tax matters—We conduct operations through our various subsidiaries in countries throughout the world. Each country has its own tax regimes with varying nominal rates, deductions and tax attributes. From time to time, we may identify changes to previously evaluated tax positions that could result in adjustments to our recorded assets and liabilities. Although we are unable to predict the outcome of these changes, we do not expect the effect, if any, resulting from these adjustments to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows.