U.S vs. Windsor comes before the Supreme Court this week as a challenge to DOMA. The case involves $363,000 that Edith Windsor was required to pay in estate taxes when her wife, Thea Spyer, passed away in 2009. Had Windsor been married to someone of the opposite sex, her taxable estate income would have been zero.
In terms of Social Security, same-sex couples are ineligible to claim spousal benefits or collect survivor benefits if their spouse dies. According to a 2009 study by the Williams Institute at UCLA, gay couples receive $3,060 less a year than their heterosexual counterparts and lesbian couples receive $5,412 less.