While two recent controversial U.S. Supreme Court decisions will not affect Nebraska's ban on same-sex marriages, the state could be vexed by a ruling Thursday from the IRS that will allow some same-sex couples to file joint federal tax returns starting in 2014.

Under Thursday's “state of celebration” ruling, any same-sex couple possessing a marriage license from any U.S. state that allows same-sex marriage may jointly file a federal tax return — no matter where they live. The ruling will create some complications for Nebraska and the 23 other states that do not recognize same-sex marriage but require taxpayers to reference the federal tax return when filling out their state tax forms, according to the Tax Foundation, a nonpartisan tax research group.

Until Thursday's ruling, federal benefits, such as jointly filing on federal income taxes, were tied to a married couple's place of residence.

“Using a 'state of celebration' standard may be more realistic and accurate, but it will present challenges in compliance and enforcement that would not occur under a 'state of residence' standard," said Joseph Henchman, vice president of state and legal projects at the Tax Foundation.

Also Thursday, the U.S. Department of Health and Human Services said that legally married same-sex couples, regardless of where they live, are eligible for Medicare benefits that previously were afforded only to traditional married couples.

As for the IRS ruling, the foundation said same-sex couples in Nebraska and the other 23 states will be able to file joint federal income tax returns but need guidance on how to prepare their state returns. Assuming a state does not opt to recognize same-sex marriage by next year, the Tax Foundation said viable options include:

* Permitting taxpayers to reference a “dummy” federal return reflecting single filing status for their state return.

* Permitting taxpayers to 'split' a joint federal return down the middle, using one-half for each single state return.

* Creating a new filing status permitting any taxpayer who files a joint federal return to file a joint state return, especially if the state presently recognizes civil unions or domestic partnerships.

Nebraska Tax Commissioner Doug Ewald did not immediately respond to a request for comment.

There are no states that prohibit same-sex marriage while recognizing same-sex marriages performed in other states.