The Supreme Court’s ruling in United States v. Windsor last year requires federal recognition of same-sex marriages obtained in states that have passed laws recognizing the same. One of the many benefits for same-sex spouses is the ability to amend prior tax returns to file jointly.
TurboTax has a calculator specifically for same-sex couples to determine if it would be worth amending their prior returns. Lifehacker has the story here.
Same-Sex Spouses May Amend Prior Tax Returns for Larger Refunds