Marginal Tax Rate Calculator
Created by: Daniel Hayes
Last updated:
Find the federal tax bracket your next dollar falls into, your combined marginal rate including FICA and state, plus scenario modeling for earning an extra $1k–$25k.
Marginal Tax Rate Calculator
FinanceFind the tax bracket your next dollar of income falls into, including federal, FICA, and state combined marginal rates.
What is a Marginal Tax Rate Calculator?
A marginal tax rate calculator identifies the federal income tax bracket your current income sits in and shows the rate applied to any additional income you might earn.
It helps answer a practical question: if I earn another $5,000 or $10,000 this year, how much will I actually keep?
The marginal rate is not the rate you pay on all income — that is the effective rate.
The marginal rate applies only to income above the current bracket floor.
For planning purposes it matters most when evaluating a raise, a side income, a bonus, or a Roth conversion.
A strong marginal rate tool should show the federal bracket, the combined rate after FICA and state taxes, how far away the next higher bracket is, and a concrete scenario table showing after-tax outcomes for different income increases.
How the Marginal Tax Rate Calculation Works
The calculator looks up which 2025 federal bracket contains your taxable income and reads the rate for that bracket.
It adds the FICA marginal rate (Social Security plus Medicare for income below the wage base, Medicare only above it) and the state rate you enter to produce a combined marginal rate.
The scenario table then applies the combined marginal rate to specific income increases — $1,000, $5,000, $10,000, and $25,000 — showing how much federal tax, combined tax, and after-tax income results from each increment.
Core marginal rate relationships
Marginal federal rate = rate of the bracket containing current taxable income
Combined marginal rate = federal rate + FICA rate + state rate
After-tax income from raise = raise amount × (1 - combined marginal rate)
Example Scenarios
Example 1: $80,000 single filer
A single filer with $65,000 of taxable income is in the 22% federal bracket. Adding FICA (7.65% below wage base) and a 5% state rate brings the combined marginal rate near 34.65%, meaning a $10,000 raise yields about $6,535 after taxes.
Example 2: Approaching the next bracket
If you are $3,000 below the 24% bracket threshold, a $5,000 raise puts $3,000 in the 22% bracket and $2,000 in the 24% bracket — the blended marginal cost is between the two rates.
Example 3: Roth conversion planning
Knowing how much room remains before the next bracket helps set the maximum Roth conversion amount that stays within the current rate, preventing unnecessary spillover into a higher bracket.
How People Use This Calculator
- Evaluate the after-tax value of a raise, promotion, or bonus before negotiating.
- Determine how much Roth conversion income you can add before hitting the next bracket.
- Compare the tax cost of adding freelance income or a side project to existing wages.
- Plan year-end deductions or contributions to stay within a favorable bracket.
Tips for Better Marginal Rate Planning
Use taxable income in this calculator, not gross income.
Taxable income is gross income minus pre-tax deductions and minus the standard (or itemized) deduction.
Plugging in gross income will overstate your bracket and make the results misleading.
The combined marginal rate can surprise people.
A 22% federal bracket combined with 7.65% FICA and a moderate state rate can push the all-in marginal rate above 35%.
That context matters when deciding whether to defer income into a pre-tax account.
Frequently Asked Questions
What is the marginal tax rate?
The marginal tax rate is the percentage of tax applied to your next dollar of income. In a progressive system, it is determined by which bracket your income currently sits in.
Does earning more money push all income into a higher bracket?
No. Only the income above the bracket threshold is taxed at the higher rate. Everything below that line remains taxed at the lower brackets. This is one of the most common tax misconceptions.
Why is my combined marginal rate higher than my federal bracket?
FICA taxes (Social Security and Medicare) add roughly 7.65% to the marginal cost of each additional dollar of wages below the Social Security wage base, on top of the federal income tax rate. State income taxes stack further on top of that.
What does "income to next bracket" mean?
It is the additional taxable income needed before your marginal federal rate increases to the next bracket. It helps you understand how much room you have before a raise or bonus is taxed at a higher rate.
Sources and References
- IRS Revenue Procedure on 2025 federal income tax brackets and inflation adjustments.
- IRS FICA rate schedule and Social Security wage base for 2025.