Income Taxes	9 Months Ended
Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes On December 22, 2017, the President of the United States signed into law comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the "Act"). The Act makes significant changes to the Internal Revenue Code of 1986 with varying effective dates. The Act reduces the maximum corporate income tax rate to 21% effective as of January 1, 2018, requires companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries, broadens the tax base, generally eliminates U.S. federal income taxes on dividends from foreign subsidiaries, creates a new limitation on the deductibility of interest expense, limits the deductibility of certain executive compensation, and allows for immediate capital expensing of certain qualified property. It also requires companies to pay minimum taxes on foreign earnings and subjects certain payments from U.S. corporations to foreign related parties to additional taxes. As a fiscal year taxpayer, the Company will not be subject to many of the tax law provisions until fiscal year 2019; however, U.S. generally accepted accounting principles require companies to revalue their deferred tax assets and liabilities with resulting tax effects accounted for in the reporting period of enactment including retroactive effects. Section 15 of the Internal Revenue Code stipulates that the Company's fiscal year ending March 31, 2018, will have an estimated blended corporate U.S. federal income tax rate of 28.87%, which is based on the applicable tax rates before and after the Act and the number of days in the Company's federal tax year pro-rated for actual earnings through its October 31, 2017 tax year-end. The SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Act. SAB 118 provides a measurement period that should not extend beyond one year from the 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 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 Act. Based on a preliminary assessment of the Act, the Company believes that the most significant impact on the Company’s consolidated financial statements are as follows: Reduction of US federal corporate income tax rate: As discussed above, the Act reduces the corporate tax rate to 21%, effective January 1, 2018. For certain DTAs and DTLs, the Company has recorded a provisional deferred income tax discrete benefit of $320 million, resulting in a $320 million decrease in net deferred tax liabilities as of December 31, 2017. While the Company is able to make a reasonable estimate of the impact of the reduction in corporate tax rate, the amount will be impacted by changes in estimated deferred tax balances prior to and after December 22, 2017 for fiscal year March 31, 2018. Deemed Repatriation Transition Tax: The deemed repatriation one-time transition tax is a tax on previously untaxed accumulated and current earnings and profits (E&P) of certain of the Company's foreign subsidiaries. To determine the amount of the transition tax, the Company must determine, in addition to other factors, the amount of post-1986 E&P of the relevant foreign subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. The Company is able to make a reasonable estimate of the transition tax and recorded a provisional discrete income tax expense and related liability of $386 million. However, the Company is continuing to gather additional information to compute the amount of the transition tax, including further analysis regarding the amount and composition of the Company’s and HPES’s historical foreign earnings and taxes. The Company's accounting for the following elements of the Act is incomplete, and it is not yet able to make reasonable estimates of the effects. Therefore, no provisional adjustments were recorded. Capital expensing: The Company has not yet completed all of the computations necessary or completed an inventory of its 2018 expenditures that qualify for immediate expensing to determine a reasonable estimate. The income tax effects for this change in law require further analysis due to the volume of data required to complete the calculations. Executive compensation: As a result of changes made by the Act, starting with compensation paid in fiscal 2019, Section 162(m) will limit us from deducting compensation, including performance-based compensation, in excess of $1 million paid to anyone who, starting in 2018, serves as the Chief Executive Officer or Chief Financial Officer, or who is among the three most highly compensated executive officers for any fiscal year. The only exception to this rule is for compensation that is paid pursuant to a binding contract in effect on November 2, 2017 that would have otherwise been deductible under the prior Section 162(m) rules. Accordingly, any compensation paid in the future pursuant to new compensation arrangements entered into after November 2, 2017, even if performance-based, will count towards the $1 million fiscal year deduction limit if paid to a covered executive. The Company has not yet completed an analysis of the binding contract requirement on the various compensation plans to determine the impact of the law change. Global intangible low taxed income (GILTI): The Act creates a new requirement that certain income (i.e., GILTI) earned by controlled foreign corporations (CFCs) must be included currently in the gross income of the CFCs’ U.S. shareholder for taxable years of foreign corporations beginning after December 31, 2017. GILTI is the excess of the shareholder’s “net CFC tested income” over the net deemed tangible income return, which is currently defined as the excess of (1) 10 percent of the aggregate of the U.S. shareholder’s pro rata share of the qualified business asset investment of each CFC with respect to which it is a U.S. shareholder over (2) the amount of certain interest expense taken into account in the determination of net CFC-tested income. Because of the complexity of the new GILTI tax rules, the Company is continuing to evaluate this provision of the Act and the application of ASC 740. Under U.S. GAAP, the Company is allowed to make an accounting policy choice of either (1) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the “period cost method”) or (2) factoring such amounts into a company’s measurement of its deferred taxes (the “deferred method”). The Company's selection of an accounting policy with respect to the new GILTI tax rules will depend, in part, on analyzing its global income to determine whether we expect to have future U.S. inclusions in taxable income related to GILTI and, if so, what the impact is expected to be as well as a final determination of a tax year-end for the Company. Because whether the Company expects to have future U.S. inclusions in taxable income related to GILTI depends on not only its current structure and estimated future results of global operations but also its intent and ability to modify its structure and business, the Company is not yet able to reasonably estimate the effect of this provision of the Act in the current reporting period. Therefore, the Company has not made any adjustments related to potential GILTI tax in its financial statements and has not made an accounting policy decision. Due to anticipated future guidance to be issued by the Internal Revenue Service, interpretation of the changes in tax law and analysis of the information required to complete the calculations, the amounts recorded as a result of the Act in the period are provisional and subject to material changes. The Company will continue to analyze the Act’s impact on its consolidated financial statements and adjust the provisional amounts recorded as our analysis is completed, no later than December 2018. The Company's income tax (benefit) expense was $(341) million and $13 million for the three months ended December 31, 2017 and December 30, 2016, respectively, and $(207) million and $(25) million for the nine months ended December 31, 2017 and December 30, 2016, respectively. For the three and nine months ended December 31, 2017, the primary drivers of the effective tax rate ("ETR") were the remeasurement of deferred tax assets and liabilities as a result of the Act, the remeasurement of a deferred tax liability relating to the outside basis difference of HPES foreign subsidiaries, the accrual of a one-time transition tax on estimated unremitted foreign earnings and India dividend distribution tax (DDT) accrual on historic earnings and taxes. The primary drivers of the ETR for the three and nine months ended December 30, 2016 were the global mix of income, release of a valuation allowance in a non-U.S. jurisdiction and excess tax benefits related to employee share-based payment awards. As a result of the Merger and changes in U.S. cash requirements, a deferred tax liability of $545 million was recorded for U.S. income taxes based on the estimated historical taxable earnings of the HPES foreign subsidiaries. In addition, the Company recorded an estimated liability of $50 million for India DDT tax based on estimated historical taxable earnings of the HPES India subsidiary. These liabilities were recorded as part of acquisition accounting. As a result of the Act, the Company has changed its permanently reinvested assertion on the remaining CSC foreign subsidiaries and will no longer consider current and accumulated earnings for all non-U.S. subsidiaries permanently reinvested, except for current year Indian earnings. The deferred tax liability of $575 million has been released and the Company's estimated liability for India DDT was increased by $30 million to $80 million to include estimated historical taxable earnings for CSC Indian subsidiaries. For those investments from which the Company was able to make a reasonable estimate of the tax effects of its change in assertion, the Company has recorded a provisional estimate for withholding taxes, state taxes, and India DDT of $115 million. For those investments from which the Company was not able to make a reasonable estimate, it has not recorded any deferred taxes. The Company will record the tax effects of any change in its prior assertion with respect to these investments, and disclose any unrecognized deferred tax liability for temporary differences related to its foreign investments, if practicable, in the period that it is first able to make a reasonable estimate, no later than December 2018. In connection with the Merger, the Company entered into a tax matters agreement with HPE. HPE generally will be responsible for pre-Merger tax liabilities including adjustments made by tax authorities to HPES U.S. and non-U.S. income tax returns. Likewise, DXC is liable to HPE for income tax receivables and refunds which it receives related to pre-Merger periods. Pursuant to the tax matters agreement, the Company recorded a net payable of $24 million due to $111 million of tax indemnification receivable related to uncertain tax positions net of related deferred tax benefits, $72 million of tax indemnification receivable related to other tax payables and $207 million of tax indemnification payable related to other tax receivables. As part of the acquisition of HPES, DXC acquired uncertain tax liabilities including interest and penalties of $115 million for prior year income taxes, which are indemnified by HPE. There were no other material changes to uncertain tax positions during the three and nine months ended December 31, 2017. The IRS is examining CSC's federal income tax returns for fiscal 2008 through 2016. With respect to CSC's fiscal 2008 through 2010 federal tax returns, the Company previously entered into negotiations for a resolution through settlement with the IRS Office of Appeals. The IRS examined several issues for this audit that resulted in various audit adjustments. The Company and the IRS Office of Appeals have an agreement in principle as to some but not all of these adjustments. The Company has agreed to extend the statute of limitations associated with this audit through September 30, 2018. In addition, during the first quarter of fiscal 2018, the Company received a Revenue Agent’s Report with proposed adjustments to CSC's fiscal 2011 through 2013 federal returns. The Company has filed a protest of certain of these adjustments to the IRS Office of Appeals. The IRS is also examining CSC's fiscal 2014 through 2016 federal income tax returns. The Company has not received any adjustments for this cycle. The Company continues to believe that its tax positions are more-likely-than-not sustainable and that the Company will ultimately prevail. In addition, the Company may settle certain other tax examinations, have lapses in statutes of limitations, or voluntarily settle income tax positions in negotiated settlements for different amounts than the Company has accrued as uncertain tax positions. The Company may need to accrue and ultimately pay additional amounts for tax positions that previously met a more-likely-than-not standard if such positions are not upheld. Conversely, the Company could settle positions by payment with the tax authorities for amounts lower than those that have been accrued or extinguish a position through payment. The Company believes the outcomes that are reasonably possible within the next 12 months may result in a reduction in liability for uncertain tax positions of $14 million to $20 million, excluding interest, penalties, and tax carry-forwards.

Income Taxes

On December 22, 2017, the President of the United States signed into law comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (the "Act"). The Act makes significant changes to the Internal Revenue Code of 1986 with varying effective dates. The Act reduces the maximum corporate income tax rate to 21% effective as of January 1, 2018, requires companies to pay a one-time transition tax on certain unrepatriated earnings of foreign subsidiaries, broadens the tax base, generally eliminates U.S. federal income taxes on dividends from foreign subsidiaries, creates a new limitation on the deductibility of interest expense, limits the deductibility of certain executive compensation, and allows for immediate capital expensing of certain qualified property. It also requires companies to pay minimum taxes on foreign earnings and subjects certain payments from U.S. corporations to foreign related parties to additional taxes. As a fiscal year taxpayer, the Company will not be subject to many of the tax law provisions until fiscal year 2019; however, U.S. generally accepted accounting principles require companies to revalue their deferred tax assets and liabilities with resulting tax effects accounted for in the reporting period of enactment including retroactive effects. Section 15 of the Internal Revenue Code stipulates that the Company's fiscal year ending March 31, 2018, will have an estimated blended corporate U.S. federal income tax rate of 28.87%, which is based on the applicable tax rates before and after the Act and the number of days in the Company's federal tax year pro-rated for actual earnings through its October 31, 2017 tax year-end.

The SEC staff issued SAB 118, which provides guidance on accounting for the tax effects of the Act. SAB 118 provides a measurement period that should not extend beyond one year from the 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 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 Act.

Based on a preliminary assessment of the Act, the Company believes that the most significant impact on the Company’s consolidated financial statements are as follows:

Reduction of US federal corporate income tax rate: As discussed above, the Act reduces the corporate tax rate to 21%, effective January 1, 2018. For certain DTAs and DTLs, the Company has recorded a provisional deferred income tax discrete benefit of $320 million, resulting in a $320 million decrease in net deferred tax liabilities as of December 31, 2017. While the Company is able to make a reasonable estimate of the impact of the reduction in corporate tax rate, the amount will be impacted by changes in estimated deferred tax balances prior to and after December 22, 2017 for fiscal year March 31, 2018.

Deemed Repatriation Transition Tax: The deemed repatriation one-time transition tax is a tax on previously untaxed accumulated and current earnings and profits (E&P) of certain of the Company's foreign subsidiaries. To determine the amount of the transition tax, the Company must determine, in addition to other factors, the amount of post-1986 E&P of the relevant foreign subsidiaries, as well as the amount of non-U.S. income taxes paid on such earnings. The Company is able to make a reasonable estimate of the transition tax and recorded a provisional discrete income tax expense and related liability of $386 million. However, the Company is continuing to gather additional information to compute the amount of the transition tax, including further analysis regarding the amount and composition of the Company’s and HPES’s historical foreign earnings and taxes.

The Company's accounting for the following elements of the Act is incomplete, and it is not yet able to make reasonable estimates of the effects. Therefore, no provisional adjustments were recorded.

Capital expensing: The Company has not yet completed all of the computations necessary or completed an inventory of its 2018 expenditures that qualify for immediate expensing to determine a reasonable estimate. The income tax effects for this change in law require further analysis due to the volume of data required to complete the calculations.

Executive compensation: As a result of changes made by the Act, starting with compensation paid in fiscal 2019, Section 162(m) will limit us from deducting compensation, including performance-based compensation, in excess of $1 million paid to anyone who, starting in 2018, serves as the Chief Executive Officer or Chief Financial Officer, or who is among the three most highly compensated executive officers for any fiscal year. The only exception to this rule is for compensation that is paid pursuant to a binding contract in effect on November 2, 2017 that would have otherwise been deductible under the prior Section 162(m) rules. Accordingly, any compensation paid in the future pursuant to new compensation arrangements entered into after November 2, 2017, even if performance-based, will count towards the $1 million fiscal year deduction limit if paid to a covered executive. The Company has not yet completed an analysis of the binding contract requirement on the various compensation plans to determine the impact of the law change.

Global intangible low taxed income (GILTI): The Act creates a new requirement that certain income (i.e., GILTI) earned by controlled foreign corporations (CFCs) must be included currently in the gross income of the CFCs’ U.S. shareholder for taxable years of foreign corporations beginning after December 31, 2017. GILTI is the excess of the shareholder’s “net CFC tested income” over the net deemed tangible income return, which is currently defined as the excess of (1) 10 percent of the aggregate of the U.S. shareholder’s pro rata share of the qualified business asset investment of each CFC with respect to which it is a U.S. shareholder over (2) the amount of certain interest expense taken into account in the determination of net CFC-tested income.

Because of the complexity of the new GILTI tax rules, the Company is continuing to evaluate this provision of the Act and the application of ASC 740. Under U.S. GAAP, the Company is allowed to make an accounting policy choice of either (1) treating taxes due on future U.S. inclusions in taxable income related to GILTI as a current-period expense when incurred (the “period cost method”) or (2) factoring such amounts into a company’s measurement of its deferred taxes (the “deferred method”). The Company's selection of an accounting policy with respect to the new GILTI tax rules will depend, in part, on analyzing its global income to determine whether we expect to have future U.S. inclusions in taxable income related to GILTI and, if so, what the impact is expected to be as well as a final determination of a tax year-end for the Company. Because whether the Company expects to have future U.S. inclusions in taxable income related to GILTI depends on not only its current structure and estimated future results of global operations but also its intent and ability to modify its structure and business, the Company is not yet able to reasonably estimate the effect of this provision of the Act in the current reporting period. Therefore, the Company has not made any adjustments related to potential GILTI tax in its financial statements and has not made an accounting policy decision.

Due to anticipated future guidance to be issued by the Internal Revenue Service, interpretation of the changes in tax law and analysis of the information required to complete the calculations, the amounts recorded as a result of the Act in the period are provisional and subject to material changes. The Company will continue to analyze the Act’s impact on its consolidated financial statements and adjust the provisional amounts recorded as our analysis is completed, no later than December 2018.

The Company's income tax (benefit) expense was $(341) million and $13 million for the three months ended December 31, 2017 and December 30, 2016, respectively, and $(207) million and $(25) million for the nine months ended December 31, 2017 and December 30, 2016, respectively. For the three and nine months ended December 31, 2017, the primary drivers of the effective tax rate ("ETR") were the remeasurement of deferred tax assets and liabilities as a result of the Act, the remeasurement of a deferred tax liability relating to the outside basis difference of HPES foreign subsidiaries, the accrual of a one-time transition tax on estimated unremitted foreign earnings and India dividend distribution tax (DDT) accrual on historic earnings and taxes. The primary drivers of the ETR for the three and nine months ended December 30, 2016 were the global mix of income, release of a valuation allowance in a non-U.S. jurisdiction and excess tax benefits related to employee share-based payment awards.

As a result of the Merger and changes in U.S. cash requirements, a deferred tax liability of $545 million was recorded for U.S. income taxes based on the estimated historical taxable earnings of the HPES foreign subsidiaries. In addition, the Company recorded an estimated liability of $50 million for India DDT tax based on estimated historical taxable earnings of the HPES India subsidiary. These liabilities were recorded as part of acquisition accounting.

As a result of the Act, the Company has changed its permanently reinvested assertion on the remaining CSC foreign subsidiaries and will no longer consider current and accumulated earnings for all non-U.S. subsidiaries permanently reinvested, except for current year Indian earnings. The deferred tax liability of $575 million has been released and the Company's estimated liability for India DDT was increased by $30 million to $80 million to include estimated historical taxable earnings for CSC Indian subsidiaries. For those investments from which the Company was able to make a reasonable estimate of the tax effects of its change in assertion, the Company has recorded a provisional estimate for withholding taxes, state taxes, and India DDT of $115 million. For those investments from which the Company was not able to make a reasonable estimate, it has not recorded any deferred taxes. The Company will record the tax effects of any change in its prior assertion with respect to these investments, and disclose any unrecognized deferred tax liability for temporary differences related to its foreign investments, if practicable, in the period that it is first able to make a reasonable estimate, no later than December 2018.

In connection with the Merger, the Company entered into a tax matters agreement with HPE. HPE generally will be responsible for pre-Merger tax liabilities including adjustments made by tax authorities to HPES U.S. and non-U.S. income tax returns. Likewise, DXC is liable to HPE for income tax receivables and refunds which it receives related to pre-Merger periods. Pursuant to the tax matters agreement, the Company recorded a net payable of $24 million due to $111 million of tax indemnification receivable related to uncertain tax positions net of related deferred tax benefits, $72 million of tax indemnification receivable related to other tax payables and $207 million of tax indemnification payable related to other tax receivables.

As part of the acquisition of HPES, DXC acquired uncertain tax liabilities including interest and penalties of $115 million for prior year income taxes, which are indemnified by HPE. There were no other material changes to uncertain tax positions during the three and nine months ended December 31, 2017.

The IRS is examining CSC's federal income tax returns for fiscal 2008 through 2016. With respect to CSC's fiscal 2008 through 2010 federal tax returns, the Company previously entered into negotiations for a resolution through settlement with the IRS Office of Appeals. The IRS examined several issues for this audit that resulted in various audit adjustments. The Company and the IRS Office of Appeals have an agreement in principle as to some but not all of these adjustments. The Company has agreed to extend the statute of limitations associated with this audit through September 30, 2018. In addition, during the first quarter of fiscal 2018, the Company received a Revenue Agent’s Report with proposed adjustments to CSC's fiscal 2011 through 2013 federal returns. The Company has filed a protest of certain of these adjustments to the IRS Office of Appeals. The IRS is also examining CSC's fiscal 2014 through 2016 federal income tax returns. The Company has not received any adjustments for this cycle. The Company continues to believe that its tax positions are more-likely-than-not sustainable and that the Company will ultimately prevail.

In addition, the Company may settle certain other tax examinations, have lapses in statutes of limitations, or voluntarily settle income tax positions in negotiated settlements for different amounts than the Company has accrued as uncertain tax positions. The Company may need to accrue and ultimately pay additional amounts for tax positions that previously met a more-likely-than-not standard if such positions are not upheld. Conversely, the Company could settle positions by payment with the tax authorities for amounts lower than those that have been accrued or extinguish a position through payment. The Company believes the outcomes that are reasonably possible within the next 12 months may result in a reduction in liability for uncertain tax positions of $14 million to $20 million, excluding interest, penalties, and tax carry-forwards.