Windsor, No. 12-307 (U.S. 6/26/13), overturned the portion of the Defense of Marriage Act that had prohibited federal recognition of same-sex marriages. In August, the IRS issued Rev. Rul. 2013-17, explaining how it would treat same-sex married couples for tax purposes after Windsor (see "Tax Matters: All Legal Same-Sex Marriages Recognized for Tax Purposes," Nov. 2013, page 56).