Free calculator
Bonus tax calculator (U.S. withholding)
Estimate take-home from a standalone bonus using common U.S. federal optional flat withholding on supplemental wages (22% below the $1 million cumulative threshold, 37% on the portion above), plus employee Medicare and Social Security on the part of the bonus that still fits under the SS wage base after YTD wages you enter. This is withholding, not your final income tax—and not state tables, aggregate method, or payroll software.
When to use this calculator
Quick federal + FICA withholding check before you rely on an actual paystub—same spirit as a scratch block in Sheets or Excel.
- See how a flat federal line plus FICA changes net when you already know gross.
- Model Social Security falling to zero on the bonus when you are near or over the annual wage base.
- Rough-check the $1M supplemental threshold when you have large prior bonuses in the same year.
- Copy simple percent-of-bonus cells into a workbook—then add state and pre-tax deferrals elsewhere if needed.
We treat the bonus as supplemental wages paid in a separate check and apply the common optional flat withholding rates for federal income tax on the amounts that fall under vs over the $1 million cumulative supplemental threshold (including prior supplemental wages you type). We add employee FICA on the bonus: Medicare on the full gross, Social Security only on the part of the bonus that still fits under the annual wage base after your YTD taxable wages.
Federal income tax withholding
We split this bonus into the amount that fits under $1,000,000 cumulative supplemental wages (including YTD supplemental you entered) and the remainder. The first part uses 22%; any remainder of this bonus uses 37%—aligned with the optional flat supplemental story in IRS Pub 15 (not every employer method).
Medicare and Social Security
Medicare employee rate 1.45% applies to the full bonus here (Additional Medicare over threshold is not in v1). Social Security 6.2% applies only to the portion of the bonus that does not push cumulative covered wages over the annual wage base.
What we do not model
State or local withholding, the aggregate withholding method (bonus combined with regular wages), 401(k)/403(b) deferrals from the bonus, gross-up, multiple employers, non-cash awards, and exact employer payroll settings.
For personalized withholding, use the IRS Tax Withholding Estimator (official) or your payroll department. For generic percent-of-a-number cells, open the percentage calculator. For capital gain federal estimates (different rules), open the capital gains tax calculator.
Google Sheets & Excel (simple lines)
English US/UK patterns. These are illustrations—your employer may use the aggregate method or different state rules.
=B1*0.22Use a separate cell for the 37% slice when part of the bonus is above the $1M cumulative supplemental rule—see methodology.
=B1*0.0145Additional Medicare Tax (0.9%) is not modeled here.
=B1*0.062In a real sheet, cap 6.2% to (wage base − YTD wages) with MIN/MAX helpers—this page’s calculator does that for you.
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Frequently asked questions
What does this calculator actually estimate?
Illustrative employee-side withholding on one gross bonus: federal using the 22% / 37% optional flat split on supplemental wages (with YTD supplemental you enter), plus Medicare 1.45% and Social Security 6.2% on the capped portion. It is not your final Form 1040 tax.
Is withholding the same as the tax I owe on the bonus?
No. Withholding is what your employer sends toward taxes; your true liability depends on your full year, deductions, credits, and other income. You may owe more or get a refund when you file.
Why is federal withholding often 22% on a bonus?
For supplemental wages, employers may use an optional flat rate (22% in common IRS guidance for amounts under the cumulative $1 million threshold for the year). Your employer might use a different approved method.
What happens if supplemental bonuses exceed $1 million in a year?
Under the optional flat rules, the portion above the $1,000,000 cumulative supplemental amount is generally withheld at 37% (federal). This page splits your current bonus using prior supplemental YTD you enter.
Does the calculator include FICA on the bonus?
Yes—employee Medicare on the full gross and Social Security on the part of the bonus that still fits under the annual wage base after YTD covered wages you enter.
Why is Social Security $0 on my bonus in the results?
When YTD taxable wages (before this bonus) are already at or above the Social Security wage base, no additional 6.2% applies to the bonus. Medicare does not use that same cap in this illustration.
What about the aggregate method?
Employers may instead combine the bonus with regular wages and withhold using ordinary methods. This page does not model aggregate withholding—ask payroll or use official tools if that is your situation.
Does this include state or city tax on the bonus?
No. Only the federal + FICA lines described. State rules vary; many payroll sites offer state-specific calculators.
How do I build this in Google Sheets or Excel?
Use the copy cards for percent-of-bonus cells, then add your own state row and any cap logic for Social Security (see the SS card hint).
Where should I go for official withholding?
Start with IRS.gov—Tax Withholding Estimator for personalized checks, and Publication 15 for employer withholding tables and supplemental wage discussion.
Is this tax or payroll advice?
No. It is a free educational calculator—not a filing position and not a substitute for qualified professionals or your employer’s payroll system.