About the Bracket Comparison
Deciding whether to take a raise, pick up freelance work, or realize a big income event often comes down to one question: how much more tax will the extra income actually cost? Our Tax Bracket Comparison Calculator runs two income scenarios side by side to answer it directly.
How It Works
The calculator computes full federal tax liability for two different taxable income amounts using the same 2025 bracket structure, then reports each scenario's tax, the dollar difference between them, and the marginal rate that applies to the incremental income in the higher scenario.
Formula & Methodology
Because the US system taxes income progressively, comparing two income levels isn't as simple as multiplying the difference by a single rate, the extra income in the higher scenario might span more than one bracket, or push part of it into a new bracket entirely, while the rest of the income in both scenarios continues being taxed identically. Running each scenario through the full bracket calculation independently, rather than estimating with one flat rate, is what makes the comparison accurate. The marginal rate reported is specifically the rate on the higher scenario's last dollar, which is the rate that actually applied to the incremental income being evaluated.
Step-by-Step: Calculating It By Hand
- 1Enter the baseline taxable income (Scenario A) and the alternative or higher taxable income (Scenario B).
- 2Calculate full federal tax liability for Scenario A using the bracket structure for your filing status.
- 3Calculate full federal tax liability for Scenario B the same way.
- 4Subtract to find the dollar difference in tax between the two scenarios.
- 5Note the marginal rate on Scenario B, which shows the rate applied to the incremental income specifically.
Examples
Same bracket
$75,000 versus $95,000 taxable income (single) both stay within the 22% bracket, so the roughly $4,400 tax difference reflects a straightforward 22% rate on the $20,000 gap.
Crossing a bracket
A comparison spanning the 12%-to-22% bracket boundary shows a blended tax difference, since only the portion of income above the boundary is taxed at the higher 22% rate.
Advantages
- Runs both scenarios through the full, accurate bracket calculation rather than a flat-rate shortcut
- Clearly shows the marginal rate specifically applied to the incremental income
- Useful for evaluating a raise, bonus, freelance income, or any 'what if I earn more' question
- Works for any two income levels, not just adjacent bracket comparisons
Common Mistakes
- Assuming the entire higher income amount gets taxed at the top marginal rate, rather than just the portion in that bracket
- Forgetting this comparison is federal income tax only, excluding state tax and FICA
- Not accounting for phase-outs of credits or deductions that can make additional income cost more than the bracket rate implies
- Comparing gross income figures instead of taxable income, which can produce a misleading comparison
Edge Cases to Watch For
- If both scenarios fall within the same bracket, the tax difference is simply the income difference multiplied by that single bracket's rate.
- If the incremental income crosses one or more bracket boundaries, part of it is taxed at a lower rate and part at a higher rate, which is exactly what running full bracket calculations captures correctly.
- This comparison covers federal income tax only - state tax, FICA, or the loss of income-based credits and deductions at higher income levels aren't included.
- Some tax credits and deductions phase out as income rises, which can make the real cost of additional income higher than the marginal bracket rate alone suggests.
Common Use Cases
- Deciding whether extra income (raise, bonus, freelance work) is worth pursuing after tax
- Comparing tax impact before and after a major income change
- Illustrating how progressive brackets affect incremental income, for financial planning or client conversations
- Sanity-checking the real cost of crossing into a higher tax bracket