Should married couples file jointly or separately?

Most married couples pay less tax filing jointly, which unlocks a larger standard deduction and more credits, but not always. Filing separately can make sense in specific situations - to separate liability, when one spouse has large medical expenses measured against a lower income, or for certain income-driven student loan calculations. It can also disqualify you from some credits. The only reliable way to know is to calculate your tax both ways. Tax software makes this easy, and a tax professional can help with close calls.