In real life, same-sex couples with kids have to deal with financial and legal confusion primarily created by the Defense of Marriage Act, a 1996 law that prohibits the federal government from recognizing same-sex marriages, according to accountants and tax attorneys. Though state laws allow same-sex couples to marry legally in a growing number of places -- currently Massachusetts, Iowa, Vermont, Connecticut, New Hampshire, New York, Washington, D.C., and Washington state -- the Internal Revenue Service has to treat same-sex spouses as if they were strangers. (Maryland will join the same-sex marriage states when a new law takes effect in January 2013.)
Among many other things, the federal law bars legally married same-sex couples from receiving the same Social Security and federal pension benefits that married heterosexuals can. Same-sex spouses also pay taxes on health insurance benefits and gifts that married heterosexuals never pay.
However, the law may sometimes cut gay families a few breaks. The biggest can come from the fact that legally married same-sex couples are prohibited from filing their taxes jointly.
"Because gay couples cannot file a joint (federal) return, they are not subject to the 'marriage penalty,'" Salandra says.
Married heterosexuals can be subject to a higher tax rate than single taxpayers because their combined income can push them into a higher tax bracket. Heterosexual married couples do not have to opt for the convenience of filing jointly. But even if they claim the status of married-filing-separately, they may still pay higher taxes because they fall into different, more demanding tax brackets than single taxpayers.
Head of household: Boon for gay parents?
Gay and lesbian parents can reduce their taxes in even more ways, Salandra says.
If one parent provides more than 50 percent of a child's financial support, that parent can claim head-of-household filing status and get a higher standard deduction and lower tax rate than single taxpayers. In a same-sex household with two or more children, each partner may be able to claim head-of-household status.
However, the IRS has been challenging these kinds of filings recently, says Wendy Hartmann, a tax and estate attorney with the Los Angeles firm of Bennett & Erdman. Couples contemplating this sort of move should contact their tax advisers.