Figuring out how much federal income tax you actually owe is one of the most confusing parts of earning a paycheck. The IRS uses seven marginal tax brackets, a standard deduction that depends on your filing status, pre-tax retirement contributions that shrink your taxable income, and refundable credits like the Child Tax Credit that can cut your bill by thousands of dollars. This federal tax calculator rolls all of those pieces together using the official IRS tax-year 2024 brackets (Rev. Proc. 2023-34) so you can see your real tax before you file.
Unlike a simple withholding estimator, this tool shows you the income tax before credits, the Child Tax Credit, the net tax owed, and both your marginal and effective tax rates — so you understand not just what you owe, but why.
How to Use
- Enter your Gross Annual Income — your total salary or wages before any pre-tax deductions. If you are paid hourly, multiply your hourly rate by your annual hours; if you have a bonus or side income, include it here.
- Choose your Filing Status. Single and Married Filing Separately use a $14,600 standard deduction, Married Filing Jointly uses $29,200, and Head of Household uses $21,900. Pick the status that matches your situation on Form 1040.
- Add your Pre-Tax 401(k) Contribution if you make traditional (not Roth) 401(k) contributions. These dollars come out before income tax, so they lower your taxable income. Leave this at zero if you contribute to a Roth 401(k) or do not contribute.
- Enter your Qualifying Children Under 17. Each child who meets the IRS dependency tests qualifies for a $2,000 Child Tax Credit. The credit phases out by $50 for every $1,000 of income above $200,000 (single, MFS, HoH) or $400,000 (MFJ).
- Read the result card: it breaks out your taxable income, the federal income tax before credits, the Child Tax Credit, the net federal tax owed, your marginal (top-bracket) rate, your effective (average) rate, and your annual and monthly take-home pay.
The numbers update as you type. Move the pre-tax 401(k) slider to see exactly how much tax you save by contributing, and adjust the child count to see the credit in action.
How Federal Income Tax Brackets Work
The United States uses a progressive tax system, which means your income is taxed in chunks — not all at your highest rate. For a single filer in tax year 2024, the brackets look like this:
- 10% on taxable income from $0 to $11,600
- 12% on taxable income from $11,600 to $47,150
- 22% on taxable income from $47,150 to $100,525
- 24% on taxable income from $100,525 to $191,950
- 32% on taxable income from $191,950 to $243,725
- 35% on taxable income from $243,725 to $609,350
- 37% on taxable income above $609,350
If you earn $100,000 as a single filer, you do not pay 22% on the whole $100,000. You pay 10% on the first slice, 12% on the next slice, and 22% only on the portion above $47,150. After subtracting the $14,600 standard deduction, your taxable income is $85,400, and your total federal income tax comes to about $13,841 — an effective rate of roughly 13.8%, not 22%. That gap between your marginal rate (22%) and your effective rate (13.8%) is the single most important concept in personal tax planning.
The Standard Deduction and 401(k)
Before the brackets are applied, you get to subtract the standard deduction for your filing status. In 2024 that is $14,600 for single filers, $29,200 for married couples filing jointly, $14,600 for married filing separately, and $21,900 for heads of household. Most taxpayers take the standard deduction rather than itemizing.
Traditional 401(k) contributions work the same way: every dollar you contribute lowers your taxable income dollar for dollar. If you earn $80,000 and put $10,000 into a pre-tax 401(k), the IRS treats you as having earned $70,000 — and the tax on that $10,000 is deferred until you withdraw it in retirement.
Child Tax Credit
Families with children get a powerful break: the Child Tax Credit is worth $2,000 per qualifying child under age 17. Unlike a deduction, which reduces your taxable income, a credit reduces your tax bill dollar for dollar. The credit begins to phase out at $200,000 of income for single, head-of-household, and married-filing-separately filers, and at $400,000 for married couples filing jointly. At lower incomes, the calculator shows the full credit subtracting directly from your federal income tax.
Examples
Example 1 — A single professional earning $100,000. With the $14,600 standard deduction, taxable income is $85,400. The progressive brackets produce a federal income tax of $13,841, the marginal rate is 22%, and the effective rate is 13.8%. Annual take-home is about $86,159, or $7,180 per month — before FICA and state tax.
Example 2 — A married couple earning $150,000 filing jointly. The standard deduction is $29,200, leaving taxable income of $120,800. Their federal income tax is roughly $16,682, with a marginal rate of 22% and an effective rate of about 11.1%. Filing jointly nearly doubles the standard deduction, which is why the effective rate is so much lower than a single filer at the same income.
Example 3 — A single parent earning $80,000, saving $10,000 in a pre-tax 401(k), with two children. The 401(k) contribution drops AGI to $70,000, and the single standard deduction brings taxable income to $55,400 — about $7,241 of income tax. The two-child Child Tax Credit subtracts $4,000, leaving a net federal tax of just $3,241, an effective rate of about 4.1%. This is how dramatically pre-tax saving and credits can change your real tax bill.
Example 4 — A high earner at $1,000,000. After the $14,600 standard deduction, taxable income is $985,400, which pushes into the top 37% bracket. The federal income tax is roughly $322,786, and the effective rate climbs to about 32.3%. The Child Tax Credit is fully phased out at this income.
FAQ
What is the difference between marginal and effective tax rate?
Your marginal rate is the tax bracket your next dollar of income falls into — for example, 22% for a single filer earning between $47,150 and $100,525 of taxable income. Your effective rate is the actual percentage of your gross income that you pay in federal tax, calculated as net tax divided by gross income. Because of the standard deduction and the progressive brackets, your effective rate is always lower than your marginal rate.
How much federal tax do I pay on $100,000?
For a single filer in tax year 2024, $100,000 of gross income minus the $14,600 standard deduction leaves $85,400 of taxable income. The progressive brackets produce roughly $13,841 of federal income tax, an effective rate of about 13.8% and a marginal rate of 22%. This does not include FICA (Social Security and Medicare) or state income tax.
Should I take the standard deduction or itemize?
In 2024, about 90% of taxpayers take the standard deduction because it exceeds the sum of their itemized deductions (mortgage interest, state and local taxes capped at $10,000, charitable gifts, and medical expenses above 7.5% of AGI). If your itemized deductions total more than $14,600 (single) or $29,200 (MFJ), it may pay to itemize. This calculator uses the standard deduction; raise the deduction field if you itemize.
How does a pre-tax 401(k) lower my tax?
Traditional 401(k) contributions are made with pre-tax dollars, so every $1 you contribute reduces your taxable income by $1. If you are in the 22% bracket, each $1,000 contribution saves you about $220 in federal tax today. The money grows tax-deferred and is taxed when you withdraw it in retirement. Use the Pre-Tax 401(k) slider in this calculator to model your savings.
What is the Child Tax Credit and who qualifies?
The Child Tax Credit is worth $2,000 per child under age 17 who meets the IRS dependency tests. It is a credit, meaning it reduces your tax bill dollar for dollar. It begins phasing out at $200,000 of income for single, head-of-household, and MFS filers, and at $400,000 for married couples filing jointly. Enter the number of qualifying children in this calculator to see the credit applied.
Does this calculator include FICA or state tax?
No. This calculator estimates federal income tax only. It does not include the 7.65% FICA payroll tax (6.2% Social Security up to the wage base plus 1.45% Medicare), state income tax, or local taxes. Your real total tax burden will be higher than the figure shown here.
What is the highest federal tax bracket?
The top federal income tax bracket in tax year 2024 is 37%. It applies to taxable income above $609,350 for single and MFS filers, $731,200 for married filing jointly, and $609,350 for heads of household.
Disclaimer
This federal tax calculator is provided for informational purposes only and does not constitute tax, legal, or financial advice. Estimates are based on the official IRS tax-year 2024 brackets (Rev. Proc. 2023-34), the standard deduction, pre-tax 401(k) contributions, and the Child Tax Credit as described; they do not include FICA, state or local taxes, itemized deductions, other credits, or the Alternative Minimum Tax. Actual tax liability depends on your full tax return, deductions, credits, and circumstances. Always consult a qualified tax professional or use official IRS resources before filing.