Filing Status
Also called: married filing jointly, head of household, single filer
Filing status determines your bracket thresholds and standard deduction — single, married filing jointly, married filing separately, head of household, or qualifying widow(er). It's set by your situation on the last day of the tax year, so a December wedding counts for the whole year. Head of household is the most commonly missed: it gives a single parent materially better brackets than filing as single.