This year, as tax day approaches, tax experts say even legally married gay couples are inviting the wrath of the IRS by filing their taxes jointly as a married couple – particularly if the status means they will end up paying less in taxes to the government.

Tax law allows heterosexual couples who are married to divide their incomes when they file jointly, which typically results in a lower tax rate.

Then what should gay couples do? Better to file as singles, say tax preparers, or to calculate their taxes as married filing separately, then submit the return that forces them to pay the most.

"Even if you're wrong in the end, you don't face the consequence of underpaying," Attorney Jamie Pedersen, told the Seattle Times. "You're not in the position of owing back taxes, interest and penalties, said the a Seattle lawyer who sits on the board of Lambda Legal, the national legal-advocacy group.

Moreover, said Pedersen, filing this way “keeps you on the moral high ground, showing that you're willing to undertake the obligations that go along with marriage."

Lambda and other groups also are recommending gay couples who file returns as single taxpayers disclose to the IRS that they are married but are filing as singles in light of the federal Defense of Marriage Act, or DOMA, which recognizes marriage only between one man and one woman. The couples can do so either by noting it on their return with an asterisk next to the status box, including a cover letter, or submitting a disclosure form that many gay-rights groups are circulating.

The IRS says it’s simply a matter of administration policy. "For decades people have been sending various types of materials, regarding various issues, with their tax returns, which become part of that return," IRS spokeswoman Judy Monahan said. "Our main focus is processing the return. We take seriously the administration of the tax laws, but we do not make policy" on gay marriage.

Lambda notes that the IRS has begun warning tax preparers, businesses and state governments that same-sex couples legally married in Massachusetts or registered as domestic partners in states such as California and New Jersey must file separate income tax forms.

Citing DOMA, the IRS says that the government does not recognize anything other than legally married opposite-sex couples.

Attempts to file a joint returns could lead to fines or other penalties, warns Lambda.