Marginal vs Effective Tax Rate: Debunking the 'Bracket Bump' Myth

Why "I'll move into a higher bracket" is a costly misconception

The US federal income tax is progressive: each bracket's rate applies ONLY to dollars within that bracket, never to your whole income. A single filer at $75,000 gross has $60,000 taxable (after the $15,000 standard deduction). The first $11,925 is taxed at 10%, the next $36,550 at 12%, and the remaining $11,525 at 22%. The "marginal rate" is 22% — the rate on the next dollar. The "effective rate" is the actual tax (~$8,900) divided by taxable income — about 14.8%, far below the marginal.

A $1,000 raise pushes you $1,000 further into whatever bracket you're in. If that bracket is 22%, the raise costs $220 in federal tax — you keep $780. It can NEVER cost more than that, no matter how close to a bracket boundary you are. The "bracket bump" myth — that a raise can leave you worse off — is just wrong in the federal income tax. (It can be true for income-tested benefits like Medicaid eligibility cliffs, but that's a different system.)

How the math works

1. Taxable income = gross income − standard deduction ($15,000 single / $30,000 MFJ in 2025).
2. Tax = walk the progressive brackets — 10% / 12% / 22% / 24% / 32% / 35% / 37% — and sum the rate × slab-width for each slab your taxable income spans.
3. Marginal rate = rate of the top bracket your income reaches (the rate on the NEXT dollar).
4. Effective rate = total tax ÷ taxable income. Always lower than marginal once your income spans more than one bracket.
5. Tax on next $1,000 = marginal rate × $1,000. The real cost of a raise.

Sources: IRS Rev. Proc. 2024-40 for the 2025 brackets and standard deductions, and IRS Publication 17 on how the progressive system works.

What this simplifies: ignores state income tax, FICA (Social Security + Medicare), credits, and itemized deductions. Real take-home is also reduced by payroll taxes (7.65% for employees) and any state tax (0-13.3% depending on state). The federal marginal rate you see here is the federal piece only.

Math runs locally. Inputs never leave your browser. Source on github.

Where this calculation doesn't apply

• Benefit cliffs. The "bracket bump" myth is wrong for income tax, but income-tested government benefits (Medicaid, ACA subsidies, FAFSA) have real cliffs — crossing a threshold can lose a benefit that exceeds the income gain. That's a separate system and isn't modeled here.
• Tax credits with phaseouts. Some credits (EITC, Child Tax Credit, Premium Tax Credit) reduce by a percentage of income above a threshold. This raises the effective marginal rate on income in the phaseout range, often well above the headline bracket. Not modeled here.
• You itemize deductions. If you itemize (mortgage interest, SALT capped at $10k, charitable giving), your taxable income differs from gross − standard deduction. Recompute with your actual taxable income.
• Capital gains or qualified dividends. Those are taxed at their own LTCG bracket rates (0% / 15% / 20%), not the ordinary brackets shown here. See the Capital Gains Harvesting tool.

What to actually do

1. Use your real taxable income (from your 1040 line 15), not gross — the standard-deduction default here is a rough proxy.
2. Take the raise. The federal tax on it can never exceed the marginal rate × the raise amount.
3. If you're near a benefit cliff (ACA subsidy, Medicaid), check those specific phaseouts — that's where real "raise hurts" math can hide.
4. To reduce taxable income legitimately: pre-tax 401(k), traditional IRA, HSA, or itemized deductions if they exceed the standard. See the related tools.