After months of silence in the wake of the U.S. Supreme Court striking down Section 3 of the Defense of Marriage Act (DOMA), the IRS has finally issued definitive guidance on the issue. (IRS Revenue Ruling 2013-17) The IRS now says that same-sex married couples will be treated the same as traditional married couples for all federal tax purposes, including income, gift and estate taxes. Any same-sex marriage legally entered into in one of the 50 states, the District of Columbia, a U.S. territory, or a foreign country is covered by the ruling.
Generally, couples will have three years from the date a tax return was filed to apply for an income tax refund. Use Form 1040X, Amended U.S. Individual Tax Return.