The U.S Department of Treasury and the Internal Revenue Service (IRS) ruled on August 29, 2013 that same sex couples who are legally married in jurisdictions that recognize their same sex marriage, will be treated as married for federal tax purposes. The ruling applies regardless of whether the couple lives in a jurisdiction that recognizes same-sex marriage or not.
Under the ruling, same-sex couples will be treated as married for all federal tax purposes, including income as well as gift and estate taxes. The ruling applies to all federal tax provisions where marriage is a factor, including filing status, claiming personal and dependency exemptions, taking deductions, employee benefits, contributing to an IRA and claiming the earned income tax credit or child tax credit.
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 will be covered by the ruling. However, the ruling does not apply to registered domestic partnerships, civil unions or similar formal relationships recognized under state law.