There is no bonus tax — there is bonus withholding
The IRS treats bonuses as supplemental wages. Paid separately from a regular paycheck, they can be withheld at a flat 22% federal rate — the percentage method this calculator models. FICA still applies on top: Social Security while your wages are under the annual base, and Medicare on every dollar. None of this is the final tax; the final tax is settled on your return, where a bonus is simply income.
withheld = bonus × 22% federal + Social Security + MedicareWorked example · $5,000 bonus on an $85,000 salary
- Federal withholding: $5,000 × 22% = $1,100.
- Social Security: $5,000 × 6.2% = $310 — the salary leaves plenty of room under the wage base.
- Medicare: $5,000 × 1.45% = $72.50.
- Net bonus: $3,517.50 — 29.7% withheld in total.
Why your salary is asked for
Two thresholds depend on wages you have already earned. Social Security stops once the year’s wages reach the annual base — a large bonus on a large salary may owe little or none of it. And Additional Medicare withholding starts once total wages pass $200,000. Entering your regular salary lets the calculator place the bonus correctly against both lines rather than pretending it exists in isolation.
Withholding today, truth in April
The flat rate makes the payday maths simple; your real bill arrives with the return. To see what the bonus adds to your year’s tax, put your salary with and without it through the federal income tax calculator and compare. For what the payroll taxes alone take, the FICA calculator isolates them; and if the bonus lands inside a regular paycheck, the paycheck calculator models that combined check.
What’s included, and what isn’t
Every figure this calculator produces is an estimate. Here is exactly what it accounts for, and what it does not.
What’s included
- Federal withholding at the 22% optional flat rate, and at the mandatory 37% on supplemental wages beyond $1,000,000 a year.
- Social Security on the bonus, respecting the annual wage base your salary has already used.
- Medicare, plus Additional Medicare withholding where salary and bonus together pass $200,000.
- The net bonus and the share withheld.
What’s not included
- The aggregate method, where the bonus is added to a regular paycheck and withheld from the W-4 tables — ask payroll which they use.
- State income tax on bonuses, which many states withhold at their own supplemental rates.
- 401(k) or other deductions your employer may apply to bonus pay.
- Your final tax on the bonus, which depends on your whole year and is settled on your return.
What this calculator assumes
- The bonus is paid separately from regular wages and withheld under the percentage (flat-rate) method.
- Your regular salary is treated as already using the Social Security wage base first; the bonus takes whatever room remains.
- Additional Medicare Tax follows the employer withholding rule: a flat $200,000 of wages, regardless of filing status.
- Bonuses are not taxed at a special rate on your return — the flat rate is only how withholding is calculated on the day.
Sources
Every rate and threshold above is transcribed from a primary source and re-checked on the date shown.
Frequently asked questions
Why is my bonus taxed at 22%?
It is not taxed at 22% — it is withheld at 22%. When a bonus is paid separately from regular wages, the IRS lets employers withhold a flat 22% federal rate instead of running the W-4 tables. On your tax return the bonus is ordinary income, taxed at your normal brackets; the flat withholding is just a down payment that gets reconciled there.
Do Social Security and Medicare come out of a bonus?
Yes. A bonus is FICA wages like any other pay: 6.2% Social Security (until your year's wages reach the annual wage base) and 1.45% Medicare, plus the 0.9% Additional Medicare withholding once your total wages pass $200,000. That is why more than 22% usually comes out.
What is the aggregate method?
The other way employers can withhold on a bonus: add it to a regular paycheck and run the whole amount through the normal W-4 withholding tables. It often withholds more than the flat method for the same bonus, because the tables treat the inflated check as if you earned that much every period. Ask payroll which method they use — this calculator models the flat percentage method.
When does the 37% rate apply?
Once your supplemental wages for the calendar year pass $1,000,000, every dollar beyond that must be withheld at 37% — no employee choice, no W-4. The advanced field lets you enter bonuses already paid this year so the calculator applies the threshold correctly.
Will I get some of the withholding back?
Quite possibly. If your marginal tax rate is below 22%, the flat withholding overpays and the difference comes back in your refund. If you are in a higher bracket, 22% under-withholds and you may owe at filing. The effective tax on a bonus is ultimately set by your whole year's income, not by the day it was paid.