Lawmakers annually match up Idaho's tax code with the federal one, to ease filings for state residents.
This year, however, what's normally an innocuous vote was fraught with partisan tensions.
That's as minority Democrats protested a provision barring same-sex couples legally married elsewhere from filing joint Idaho tax returns -- even though they can file jointly with the Internal Revenue Service.
Thursday's 57-12 House vote was along party lines.
Idaho Falls Republican Rep. Janet Trujillo argued Idaho's 2006 gay-marriage ban left lawmakers no option than barring joint filings -- though it could add cost and hassle to gay couples.
Meanwhile, Boise Democratic Rep. Grant Burgoyne countered this denied Idaho residents equal protections.
Burgoyne says Idaho will eventually lose in court, unnecessarily costing the state legal fees.
Senators still must vote.