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.