DayCents

Marginal Tax Rate

Your marginal tax rate is the rate you pay on your last dollar of income — the tax bracket your top dollar falls into. Because the US uses progressive brackets, it's higher than your effective (average) rate: moving into a higher bracket only taxes the income above that threshold, never your whole income.

This is the number for decisions at the edge, because a deduction saves tax at your marginal rate rather than your average one: a $7,500 pre-tax contribution in the 22% bracket cuts the bill by $1,650, so the contribution costs $5,850 of take-home pay. It is also the rate to use when judging overtime, a bonus, or a side income, since those dollars stack on top of everything else. Two things push your true marginal rate above your federal bracket: state income tax, which adds directly on top, and income-based phase-outs of credits and deductions, which can make an extra dollar cost more than the bracket alone implies.