Alas, there's no bonus for the never-marrieds, divorced, widowers and widows. They're the Rodney Dangerfields of the tax code. They get no respect. The marriage penalty hits two-earner couples whose incomes are fairly close. They pay more as a couple than they would as two singles.
Tax brackets are to blame.
As a single person, the lower earner is taxed in the 15 percent bracket. But when those earnings are piled on top of a spouse's income, they're moved into the higher 28 percent bracket. So taxes rise. The tax bill proposed by Congress helps married couples in two ways. Today, it's only 67 percent more.