This warning may come somewhat late in the game, but if you're married and you have any reason to suspect that your spouse may be a deadbeat, don't file a joint tax return. That's because if he (and usually it's a he; the dire scenario I outline here mostly affects women) cheats on his taxes and then leaves you (because that's just the sort of scumbag he is, and you should have listened to your mother all along), the IRS will make you pay back taxes and penalties on his income. This is what's known as the "joint liability" provision of the tax code. As the IRS explains it on its Web site, "One spouse may be held responsible for all the tax due even if the other spouse earned all the income or claimed improper deductions or credits."
In the New York Times today, law professor Shari Motro says that millions of women are subject to such penalties on income earned by their spouses. That's because the vast majority of married couples file taxes jointly, meaning that each spouse pays taxes on just half the income that the couple makes. This creates a significant benefit for some married people, especially in couples where one person makes a lot and the other does not (what some people might call the "traditional marriage"). For instance, say one spouse makes $100,000 and the other makes nothing -- filing jointly allows the high-earning member to pay taxes on only half that, 50 large, greatly reducing the tax bill.
Motro explains that the "theory behind treating spouses as if they each earned half of the couple's combined income is that marriage is presumed to indicate economic unity between two people." Of course, marriage is also presumed to indicate love and eternal togetherness, but sometimes things don't work out that way. Indeed, in most states the low earner has no right to the high-earning spouse's income in the event of a breakup, even after the high earner has profited by telling the IRS that the low-earning spouse essentially made half the couple's money. So when the marriage falls apart, the low-earning partner doesn't get the money claimed as income and is left holding the bag for back taxes.
Motro reports that there are efforts in Congress to fix this problem, but she says they all miss one fundamental fact -- that though married couples file jointly, many don't truly share their money. Motro argues for a novel arrangement: Instead of using marriage as a "proxy" for economic unity, she says, why not require actual economic unity among couples who want the bonus of filing jointly? What she means is that instead of requiring people to be married when they file taxes jointly, the law should, instead, force them to simply share their income. This allows people to get the benefit of filing jointly -- lower taxes -- but also helps the low-earning partner in a relationship that might head south. When (or, OK, if) the couple splits up, they'll share both the joint income and the tax liability on that income.
And there's another bonus to Motro's set-up: "Making economic unity, rather than marriage, the requirement for joint filing would provide a rare opportunity for moderate conservatives and liberals to agree on a reasonable approach to the reality of same-sex households while staying clear of the quagmire of gay marriage," she writes. In other words, because you wouldn't need to be "married" to be economically tied together, even gay people could do it!
But that's just Motro's suggestion, and it's not anywhere close to becoming law. So what should you do now, one day before tax day? If you're the low-earning spouse in a relationship that these days feels about as authentic as the TomKat show, you might try asking him -- or her -- to promise (perhaps in writing?) that if you break up, he (or she) will actually give up half the joint income. If she (or he) doesn't agree, don't file jointly. (But I am not a lawyer! This is not legal advice! I've got enough tax problems of my own.)