For federal tax purposes, the IRS has declared that it will recognize all same-sex marriages. The U.S. Department of Labor issued similar guidelines in September 2013. This means same-sex married couples can take advantage of all the special IRA [and 401(k)] rules applicable to any spouse.
For tax years 2013 and later, the IRS requires “married” tax-filing status for federal tax returns filed by legally married, same-sex couples, whether or not they live in a jurisdiction that recognizes same-sex marriages. In states that do not recognize same-sex marriages, the state tax return would still require each person to file as “single.”