See the LGBT law area of Nolo's website for updates in this area, including the Supreme Court's ruling in the Obergefell v. Hodges case in 2015 making same sex marriage legal in all states.
Under rules issued by the U.S. Department of Treasury in 2013, same-sex couples who are legally married in any state are treated as married for federal tax purposes, regardless of whether or not the state where they reside recognizes same-sex marriages. The Treasury’s ruling came in the aftermath of the Supreme Court decision in the Windsor case striking down key provisions of the Defense of Marriage Act (DOMA), including a provision relied on by the IRS to deny same-sex couples the right to file as married couples.
After the Windsor case, the IRS was required to allow same-sex couples who are legally married under state law to file as a married couple. However, because the IRS used state of residency to determine a person’s tax filing status, there was concern that same-sex spouses who lived in a state that didn’t recognize same-sex marriage would be treated as single for federal tax purposes. The Treasury’s ruling that all legally married same-sex couples will be treated as married for federal tax purposes regardless of where they live eliminates any possible confusion about filing status for same-sex couples. It also provides them with the assurance that they can change their state of residency without worrying about jeopardizing their married filing status. The IRS ruling covers any same-sex marriage legally entered into in any of the 50 states, the District of Columbia, a U.S. territory, or a foreign country; it does not apply to registered domestic partnerships, civil unions, or similar formal relationships recognized under state law.
Starting with 2013 tax return filings, all same-sex couples who are legally married must file their federal income tax returns using the married filing jointly or married filing separately filing status. The effective date of the Treasury’s ruling is September 16, 2013. Same-sex spouses who file a 2012 tax return after that date (because of extensions) can choose either single or married for their filing status. Same-sex spouses who filed a 2012 tax return prior to September 16, 2012, or a 2011 or earlier tax return can amend their prior tax returns to change their filing status to married, provided the statute of limitations for filing an amended tax return has not expired. Generally, taxpayers have three years from the date of filing or two years from the date the tax was paid, whichever is later, to file an amended return.
In addition to the change in filing status, same-sex couples will be treated as married for all purposes under federal tax laws, including income and gift and estate taxes. They will be entitled to take advantage of benefits provided to married couples, such as claiming personal and dependency exemptions, taking the standard deduction, employee benefits, contributing to an IRA, and claiming the earned income tax credit or child tax credit.