Today's announcement from the Treasury Department and the Internal Revenue Service (IRS), which says that same-sex couples who are legally married in jurisdictions that recognize their marriages will be treated as married for federal tax purposes, is newsmaking for immigration reasons, too. If a U.S. citizen or lawful permanent resident plans to sponsor a same-sex foreign national for a green card, one of the tasks the couple will face is proving a bona fide marriage -- that is, that the couple is really establishing a life together, not just committing a fraud to get the foreign-born person a green card.
A heterosexual couple will typically provide this proof in the form of documents like wedding photos, affidavits from friends and family, children's birth certificates, and . . . copies of joint income tax returns. No one of those documents is absolutely required, but a nice-sized packet of some combination of them is going to be more convincing than a scant few documents.
But, in cases where a same-sex couple has been focused on remaining closeted, compiling even a few of these documents can be a challenge. That's why this new opportunity to file a joint tax return -- or at least one indicating "married filing separately" -- will come in handy. In fact, it works retroactively. You can file an amended return for last year, or up to three years ago -- and potentially collect a refund!
A couple of other notes on the IRS decision. It clarified that the current place of residence of the couple doesn't matter. If they were married in a state or country where same-sex marriages are legally recognized, the IRS will recognize it too. In fact, the IRS will go beyond recognition: It will mandate that the couple file as a married couple. However, the ruling does not extend to registered domestic partnerships, civil unions, or similar relationships recognized under state law.
For more information on federal rights for same-sex couples, to do with immigration, financial, family, and other matters, see the "LGBT Law" section of Nolo's website.