On May 15, 2014, the IRS issued Notice 2014-37, which provides that mid-year amendments to safe harbor 401(k) plans that are made to comply with the US Supreme Court's decision in United States v. Windsor will not cause the plan to fail the IRC Section 401(k) or (m) safe harbor requirements.

Generally, IRC Sections 401(k) and (m) provide that plan amendments for safe-harbor 401(k) plans must be made before the plan year begins and remain in effect for a full 12 month plan year. In the Windsor decision, the US Supreme Court ruled that Section 3 of DOMA, which defined the terms "spouse" and "marriage" for purposes of federal law as being solely between one man and one woman, was unconstitutional. In Notice 2014-19, the IRS explained that qualified retirement plans must generally be amended to comply with the Windsor decision by December 31, 2014 (see Practice Note, Impact of U.S. v. Windsor and Related Guidance on Qualified Retirement Plans and Impact of US v. Windsor and Related Guidance on Qualified Retirement Plans Checklist).

Notice 2014-37 clarifies that the adoption of a mid-year amendment to comply with Windsor will not cause a Section 401(k) or (m) safe harbor plan to fail to meet the safe harbor requirements of IRC Sections 401(k) and (m).

For more information on safe-harbor 401(k) plans, see Practice Note, Safe Harbor 401(k) Plans: Overview and Planning Opportunities.