The federal government has made some things clear: Same-sex couples married in any jurisdiction that permits such unions must now file their federal returns as married, even if they live in a state that doesn’t recognize their marriage. But the rules for state tax filings still follow the law of the state where they reside, and that can make things sticky. Plus, the situation is fluid in many states, with court challenges being mounted in many states.

Those living in states that OK their marriage will file state returns as married. Those states are California, Connecticut, Delaware, Hawaii, Illinois, Iowa, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New Mexico, New York, Rhode Island, and Vermont, as well as the District of Columbia. The same holds for married same-sex couples living in Colorado, Missouri, and Oregon, even though those three locales currently prohibit same-sex marriage in their states.

Utah — which also doesn’t permit same-sex marriage — is allowing couples to choose whether to file as married or single for the 2013 tax year as the broader fight over same-sex marriage in that state continues in the courts. Legally married same-sex couples in other states, who will have to file as single, should plan on spending extra time on their tax returns. Since states typically base tax returns on federal tax returns, these couples may have to create “dummy” federal tax returns as single filers before they can complete their state tax returns.

States currently requiring same-sex couples to continue to file singly are Alabama, Arizona, Arkansas, Georgia, Idaho, Indiana, Kansas, Kentucky, Louisiana, Michigan, Mississippi, Montana, Nebraska, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin. And, of course, if you live in Alaska, Florida, Nevada, South Dakota, Texas, Washington, or Wyoming, the question is moot: There’s no income tax at all.

Filing a state tax return can be tricky for same-sex couples. Those who were married in any jurisdiction that permits such unions must now file their federal returns as married, even if they live in a state that doesn’t recognize their marriage. However, the rules for state tax filings still follow the law of the state where they reside.

Those living in states that OK their marriage will file state returns as married. The same goes for married same-sex couples living in Colorado, Missouri, and Oregon, even though those three locales currently prohibit same-sex marriage in their states. Utah — which also doesn’t permit same-sex marriage — allows couples to choose whether to file as married or single.

Legally married same-sex couples in other states, who will have to file as single, should plan on spending extra time on their tax returns. Since states typically base tax returns on federal tax returns, these couples may have to create “dummy” federal tax returns as single filers before they can complete their state tax returns.