Following President Bush's endorsement of a constitutional ban on same-sex marriage, a conservative, “pro-family” organization wrote the IRS Commissioner to alert him about “a potential fraudulent tax scheme.” The organization was alarmed by “rebellious state and local officials reportedly permitting persons of the same sex to marry in flagrant disobedience of applicable laws defining marriage as a union between a male and a female,” and was further alarmed by the prospect that these “married” same-sex couples (their quotes, not mine) might attempt to file joint federal income tax returns. The organization urged the Commissioner to deter these individuals from attempting to evade income tax by threatening to investigate and prosecute any same-sex couples who attempt to file joint returns.

In [its response], the IRS went beyond the narrow circumstances that alarmed the conservative organization and spoke more generally about the ability of married same-sex couples to file joint federal income tax returns. Citing section three of the Defense of Marriage Act (DOMA), which precludes the recognition of same-sex marriages for purposes of federal law, the IRS reassured the organization that

Putting aside the questionable constitutionality of DOMA, the IRS was technically correct in making this statement – but only because the statement was confined to the tax treatment of domestic same-sex marriages.