Indiana would break from an Internal Revenue Service policy recognizing same-sex marriage for tax purposes if a late-session change becomes law.
The Senate on Monday approved adding the language to another tax bill. The measure is up for a final vote in the chamber Tuesday.
The IRS last year announced all same-sex marriages would be recognized in federal tax returns. The ruling applies regardless of whether the couple lives in an area where their marriage is recognized.
If passed into law, the Indiana bill would split from the IRS and not grant same-sex couples the same tax breaks other couples now receive.
Republican Sen. Brandt Hershman of Buck Creek says blocking the benefits would match Indiana tax policy with the state ban on same-sex marriage.