Marginal Tax Rate Calculator
This calculator provides a practical, combined estimate of the marginal tax rate that applies to incremental income by summing your federal, state, and payroll tax components. It is intended for quick scenario analysis (for example, evaluating the after-tax value of a bonus or overtime).
The result is an estimate only. It does not replace professional tax advice or a full tax return computation. Read the methodology and accuracy notes below before using results for financial decisions.
Inputs
Results
Combined marginal tax rate
31.65%
Sum of component rates (%)
3165.00%
Estimated tax on additional income
$316.50
Estimated after-tax additional income
$683.50
| Output | Value | Unit |
|---|---|---|
| Combined marginal tax rate | 31.65% | — |
| Sum of component rates (%) | 3165.00% | — |
| Estimated tax on additional income | $316.50 | — |
| Estimated after-tax additional income | $683.50 | — |
Visualization
Methodology
User-entered component rates (federal, state, payroll) are summed to produce a combined marginal rate. This approach reflects how an additional dollar of income is typically taxed across overlapping tax systems when each component applies to that same incremental dollar.
The calculator treats inputs as percentages on the marginal dollar. The payroll tax field should reflect the marginal payroll burden you personally pay on the next dollar earned (for example, employee FICA share ≈ 7.65% or self-employed combined ≈ 15.3%).
Estimates are bounded to the mathematically meaningful range (0%–100%). For precision-sensitive use cases (complex deductions, phaseouts, AMT, ACA surtaxes), run a full tax simulation or consult a tax professional.
Worked examples
Example 1: Federal 24%, State 5%, Payroll 7.65% on an extra $1,000 → Combined ≈ 36.65%, Tax ≈ $366.50, After-tax ≈ $633.50.
Example 2: Federal 37%, State 0%, Payroll 0% on an extra $10,000 → Combined = 37%, Tax = $3,700, After-tax = $6,300.
Further resources
Expert Q&A
Does this calculator compute my federal tax return or effective tax rate?
No. This tool estimates the marginal tax rate on additional income. Effective tax rate (total tax paid divided by total income) and full return calculations require comprehensive inputs—deductions, credits, capital gains, AMT, and other rules—and are beyond this quick estimator.
How should I set the payroll tax rate field?
Enter the marginal payroll taxes you personally pay on the next dollar. Employees typically use employee FICA share (about 7.65%); self-employed individuals typically include the employer and employee share (about 15.3%) unless they plan to deduct the employer-equivalent portion. Adjust if you are subject to Medicare surtax or Social Security wage base limits.
Will state tax always apply to the same marginal dollar?
State tax rules vary and some states have bracket structures and phaseouts. This calculator assumes any entered state rate applies to the marginal dollar. For detailed state-specific modeling, use a jurisdiction-specific tax calculator or professional software.
What are the tool’s limitations?
This is an estimate and does not model complex interactions such as tax credits, itemized deductions, AMT, net investment income tax, or benefit phaseouts. Results should be used for illustrative, planning, or educational purposes only.
Sources & citations
- Internal Revenue Service (IRS) - official site — https://www.irs.gov/
- Social Security Administration (FICA rates & limits) — https://www.ssa.gov/
- NIST Cybersecurity Framework (data protection best practices) — https://www.nist.gov/cyberframework
- ISO/IEC 27001 Information Security Management — https://www.iso.org/isoiec-27001-information-security.html
- IEEE - professional and technical standards organization — https://www.ieee.org/