Withholding is not the final tax
Most employers withhold a flat 22% federal tax from a bonus. Your actual tax on it depends on your bracket, so the 22% can be too much or too little:
- $35,000 salary, $5,000 bonus: $1,100 withheld, but the bonus adds only $600 of federal tax. About $500 comes back at tax time.
- $80,000 salary, $10,000 bonus: $2,200 withheld and about $2,200 owed, roughly even.
- $250,000 salary in California, $30,000 bonus: $6,600 withheld but $9,830 owed, a $3,230 shortfall, plus $3,180 of California tax.
The two withholding methods
Flat rate: 22% of the bonus, available when the employer has withheld tax from your regular pay. Aggregate: the bonus is added to a regular paycheck and taxed as if that bigger amount were your normal pay, which can withhold more or less than the flat rate. Above $1,000,000 of supplemental wages in a year, 37% is mandatory on the excess.
Source: IRS Publication 15 (2026), Supplemental wages. Also see the take-home pay calculator and our methodology.