This document contains final regulations that reflect the holdings of Obergefell v. Hodges, 576 U.S. ___, 135 S. Ct. 2584 (2015), Windsor v. United States, 570 U.S. ___, 133 S. Ct. 2675 (2013), and Revenue Ruling 2013-17 (2013-38 IRB 201), and that define terms in the Internal Revenue Code describing the marital status of taxpayers for federal tax purposes.