Shauna Griffen (L) and Brooke Shepherd show their rings after getting married at the Salt Lake County Government Building in Salt Lake City, Utah, Dec 23, 2013. US District Judge Robert Shelby in Utah on Monday refused to block his own order making same-sex marriage legal in the state, denying a request to do so by Governor Gary Herbert. [Photo/Agencies]

Same-sex couples married in Utah during a brief period when gay marriage was legal in the conservative, heavily Mormon state can jointly file their state taxes, the State Tax Commission said on Thursday.

Utah temporarily became the 18th state to legalize same-sex marriage when a US federal district judge ruled on December 20 that a state ban on gay marriage was unconstitutional. His ruling was put on hold by the US Supreme Court but not before roughly 1,400 gay couples tied the knot.

To be eligible to file joint state taxes, gay or lesbian couples must have wed before the end of the tax year, the commission said in a notice that pointed out the US Supreme Court had not issued its stay before the end of 2013. Utah is appealing the decision striking down its ban on gay marriage.

"Same-sex couples who are eligible to file a joint federal income tax return and who elect to file jointly may also file a joint 2013 Utah Individual Income Tax return," the notice from the Utah Tax Commission said.

The decision by the commission also applies to gay and lesbian couples who were married in other US states anytime before December 31, 2013, and who live in Utah, said Charlie Roberts, a spokesman for the commission.

Utah's Republican Governor Gary Herbert said last week that the state would put recognition of gay marriage on hold as it pursues an appeal. Representatives for Herbert did not immediately return calls.

The four state tax commissioners are appointed by the governor. "We've been in communication with the governor's office," Roberts said.

President Barack Obama's administration has pledged to recognize same-sex marriages in Utah even though the state will not do so.

On Tuesday, a US district judge in Oklahoma overturned the state's ban on same-sex marriage in the latest in a series of rulings by judges in federal and state courts to find that such exclusions violate the US Constitution. The judge put his decision on hold, pending an appeal of the case in Utah.