The US Department of Treasury and the IRS recently announced that all same-sex couples legally married in jurisdictions that recognize their marriages will be treated as married for federal tax purposes. This applies to all same-sex couples regardless of whether or not the jurisdiction where the couple lives recognizes same-sex marriages.
Same-sex couples will be treated as married for all federal tax purposes, including income and gift and estate taxes. In addition, the ruling applies to all federal tax provisions where marriage is a factor (i.e. filing status, personal/dependency exemptions, employee benefits, etc.)
Individuals who were in same-sex marriages prior to 2013 may go back and file amended returns in order to choose to be treated as married for federal tax purposes for one or more prior tax years still open under the statute of limitations. The statute of limitations for filing a refund claim is generally three years from the date the return was filed or two years from the date the tax was paid, whichever is later. As a result, taxpayers can still file a refund claim for tax years 2010, 2011, and 2012.
In addition, same-sex spouse health insurance coverage purchased from employers on an after-tax basis may now be treated as pre-tax and thereby excluded from income.