The IRS has recently issued guidance on how qualified retirement plans (such as 401K plans, profit sharing plans, defined benefit pension plans and 403B plans) should apply the Supreme Court’s 2013 Windsor decision, which ruled that same-sex marriages must be recognized for all federal tax purposes. While the IRS had already issued guidance indicating that all qualified retirement plans would need to prospectively recognize all same-sex marriages, it had not addressed whether plans would need to be retroactively amended to either the date of the Windsor ruling or to another date. This guidance clarifies that qualified retirement plans that have sections that would not comply with the Windsor ruling (for example, plans that refer to opposite- sex couples) must be retroactively amended to recognize same-sex spouses effective June 26, 2013. The deadline to adopt a plan amendment to this effect is the later of: 1) December 31, 2014 or 2) the cyclical remedial plan amendment period under section 5.05 of Rev. Proc. 2007-44.