Ask someone what tax bracket they're in and they might say “24%.” Ask them what percentage of their income actually went to federal tax, and the real number is almost always lower — often by 5 to 8 percentage points. This gap confuses more taxpayers than almost any other part of the tax code.
The confusion comes from a simple misunderstanding: tax brackets are marginal, not flat. Your bracket only tells you the rate on your last dollar earned — not on all of your income.
How Marginal Brackets Actually Work
The US federal system splits income into layered brackets. Each layer is taxed only on the income that falls inside it. Using the 2025 single-filer brackets:
| Bracket | Income Range (Single) | Tax on This Slice |
|---|---|---|
| 10% | $0 – $11,925 | $1,192.50 |
| 12% | $11,925 – $48,475 | $4,386.00 |
| 22% | $48,475 – $103,350 | $12,072.50 |
| 24% | $103,350 – $197,300 | Only income above $103,350 is taxed here |
Worked Example: $120,000 Salary
Say you earn $120,000 as a single filer in 2025. You are “in the 24% bracket” because your top dollar falls there. But your actual tax bill is built layer by layer:
- 10% bracket: $11,925 × 10% = $1,192.50
- 12% bracket: ($48,475 − $11,925) × 12% = $4,386.00
- 22% bracket: ($103,350 − $48,475) × 22% = $12,072.50
- 24% bracket: ($120,000 − $103,350) × 24% = $3,996.00
Total tax: $21,647.00
Divide that by your $120,000 income and your effective tax rate is 18.04% — nearly 6 points below your 24% marginal rate.
Why This Matters for Real Decisions
Two common mistakes come from confusing the two rates:
- Turning down a raise. Some people worry that crossing into a higher bracket means their whole paycheck gets taxed more. It doesn't — only the income above the threshold is taxed at the new rate. A raise never results in less take-home pay overall.
- Overestimating retirement account savings. When you contribute to a traditional 401(k) or IRA, you save your marginal rate on each dollar contributed — not your effective rate. That is actually good news: pre-tax contributions are worth more than a flat-rate calculation would suggest, because they come off the top of your income first.
Canada Works the Same Way
Canada's federal brackets are also marginal, layered on top of your province's own marginal brackets. An Ontario resident earning $120,000 CAD pays roughly a 15% federal rate at the margin plus Ontario's provincial marginal rate — but their effective combined rate lands well below the top marginal figure, for the same layering reason shown above.
See Your Real Effective Rate
Enter your income into the NorthCalc tax calculator to see your exact marginal bracket, effective rate, and take-home pay for your state or province.
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