IRS Must Decide Fate of Gay Couples in States That Don't Recognize Same-Sex Marriage

Sure to please everybody, of course

The U.S. Internal Revenue Service, already under unprecedented scrutiny, must make another tough call—whether to recognize the same-sex marriages of taxpayers whose home states don't consider the unions legal.

Underneath that big decision are dozens more stemming from the June 26 U.S. Supreme Court ruling that invalidated the federal government's definition of marriage as between one man and one woman. The IRS, which said last week it would "move swiftly," must set rules for amending prior years' returns and weigh potential penalties for under-withholding.

Each decision may mean thousands of dollars in costs or benefits to couples across the country who are trying to figure out what the court's ruling will do to personal finances that long were structured to avoid running afoul of the IRS.