On August 29, 2013, the Department of the Treasury and the Internal Revenue Service issued Revenue Ruling 2013-17.
The ruling implements the federal tax aspects of the recent U.S. Supreme Court decision in United States v. Windsor, which invalidated a portion of DOMA.
In short, the ruling provides that same-sex couples who are married in a state that allows same-sex marriage wil be treated as married for federal tax purposes even if the couple reside in a state that does not recognize sam-sex marriages.
The ruling applies to all federal tax aspects where marriage is a factor, including filing status, personal and dependency exemptions, the standard deduction, employee benefits, contributions to an IRA and the child tax credit.
However, the ruling does not apply to registered domestic partnerships, civil unions or other similar relationships recognized under state law.
More details on the ruling and its tax effect can be obtained on the IRS website.