Should married couples file jointly or separately?

Most married couples come out ahead filing jointly, which unlocks the $30,000 standard deduction, wider brackets, and credits like the child tax credit and education credits that are reduced or off-limits when filing separately. Filing separately (MFS) usually costs more in total tax, but it makes sense in specific cases: when one spouse has large income-based student loan payments tied to individual income, when there are big medical bills measured against one spouse's lower AGI, or when you want to keep tax liability legally separate. The catch with MFS is that if one spouse itemizes, both must. The only reliable way to know is to run your return both ways — good tax software computes joint vs separate side by side. Check it before assuming separate saves money; it rarely does.