On June 26, 2015, in Obergefell v. Hodges, the US Supreme Court ruled that same-sex couples may exercise the right to marry in all states and that a state may not refuse to recognize a lawful same-sex marriage performed in another state (135 S. Ct. 2584, 2607 (2015)). This decision came two years after the Supreme Court's decision in United States v. Windsor, which defined spouse for purposes of federal law to include same-sex spouses lawfully married under state law. (570 U.S. 744, 772-75) (2013).)

In response to Windsor, the Internal Revenue Service (IRS) and the US Department of the Treasury issued guidance for qualified retirement plans, including requiring that any plan qualification rule that applies because a participant is validly married must be applied to a participant who is married to an individual of the same sex under applicable state law. Many aspects of qualified retirement plans are affected by these developments, including:

Qualified retirement plans were not required to make any changes following Obergefell, because the IRS required these plans to be amended to recognize same-sex spouses and their marriages following Windsor. However, the IRS issued guidance allowing retirement plans to make certain discretionary and retroactive amendments following Obergefell (see Legal Update, IRS Notice on Obergefell Includes Permitted Cafeteria Plan Election Change and Guidance on Qualified Retirement Plans).

The Same-Sex Marriage Developments for Retirement Plans Toolkit provides many continuously maintained resources that can assist retirement plans in complying with the same-sex marriage developments in Windsor and Obergefell.