Federal Income Tax Calculator Formula

Understand the math behind the federal income tax calculator. Each variable explained with a worked example.

Use the Federal Income Tax Calculator

Formulas Used

Federal Tax

federal_tax = taxable_income <= 11600 * bracket_adj ? taxable_income * 0.10 : (taxable_income <= 47150 * bracket_adj ? 1160 * bracket_adj + (taxable_income - 11600 * bracket_adj) * 0.12 : (taxable_income <= 100525 * bracket_adj ? 5426 * bracket_adj + (taxable_income - 47150 * bracket_adj) * 0.22 : 17168.5 * bracket_adj + (taxable_income - 100525 * bracket_adj) * 0.24))

Effective Tax Rate

effective_rate = taxable_income > 0 ? (taxable_income <= 11600 * bracket_adj ? taxable_income * 0.10 : (taxable_income <= 47150 * bracket_adj ? 1160 * bracket_adj + (taxable_income - 11600 * bracket_adj) * 0.12 : (taxable_income <= 100525 * bracket_adj ? 5426 * bracket_adj + (taxable_income - 47150 * bracket_adj) * 0.22 : 17168.5 * bracket_adj + (taxable_income - 100525 * bracket_adj) * 0.24))) / taxable_income * 100 : 0

Variables

VariableDescriptionDefault
taxable_incomeTaxable Income(USD)75000
filing_statusFiling Status1
bracket_adjDerived value= filing_status == 2 ? 2 : 1calculated

How It Works

2024 Federal Income Tax Brackets (Single)

Taxable IncomeRate $0-$11,60010% $11,601-$47,15012% $47,151-$100,52522% $100,526-$191,95024%

Married Filing Jointly brackets are roughly double.

Worked Example

Single filer with $75,000 taxable income.

taxable_income = 75000filing_status = 1
  1. 0110% on first $11,600 = $1,160
  2. 0212% on $11,601-$47,150 = $4,266
  3. 0322% on $47,151-$75,000 = $6,127
  4. 04Total = $11,553, Effective rate = 15.4%

Frequently Asked Questions

What is the difference between marginal and effective tax rate?

Your marginal rate is the tax rate on your last dollar of income. Your effective rate is total tax divided by total income -- it is always lower than your marginal rate.

What is taxable income?

Taxable income is your gross income minus deductions (standard or itemized) and certain adjustments. It is the amount actually subject to tax.

When do tax brackets change?

The IRS adjusts tax brackets annually for inflation. Significant changes occur when Congress passes new tax legislation.

Learn More

Guide

Tax Bracket Guide

Understand how U.S. federal tax brackets work, the difference between marginal and effective tax rates, and strategies to reduce your tax burden legally.

Ready to run the numbers?

Open Federal Income Tax Calculator