How bonuses are withheld
Social Security = 6.2% × bonus, until wages for the year reach $184,500
Medicare = 1.45% × bonus, + 0.9% on wages over $200,000
Take-home = bonus − federal − Social Security − Medicare − state
Bonuses, commissions and other supplemental wages paid separately from your regular pay can be withheld at a flat 22% for federal income tax. Once your supplemental pay for the year passes $1 million, the employer must withhold 37% on the excess, whatever your W-4 says.
The aggregate method: instead of the flat rate, an employer can add the bonus to your regular paycheck, work out withholding on the total as if it were one normal paycheck, then subtract what was already withheld on the regular pay. Because a big single paycheck looks like a high annual salary, this often withholds more than 22%. Your employer chooses the method; this calculator uses the flat rate.
Gross-up: to hand someone a set amount after withholding, divide by what's left after the rates. With no state tax and wages under the limits: gross = net ÷ (1 − 0.22 − 0.062 − 0.0145) = net ÷ 0.7035.
Worked example
A $10,000 bonus to someone who has earned $50,000 so far this year: federal $2,200, Social Security $620, Medicare $145. Take-home: $7,035.
To give an employee $1,000 after withholding: $1,000 ÷ 0.7035 = $1,421.46…, rounded up to $1,421.47.
Good to know
- Withholding isn't your final tax. Your bonus is taxed with the rest of your income when you file. If your bracket is 12%, you'll likely get some back; if it's 32% or more, you may owe.
- State rules differ: some states have their own supplemental rate, and some have no income tax. Enter your state's rate if you know it.
- 401(k) deferrals from the bonus, if your plan takes them, aren't included. Local taxes aren't either.
Sources
- IRS Publication 15 (2026) – 2026: 22% supplemental rate, 37% over $1 million, aggregate procedure; 6.2% and 1.45%; $184,500
- IRS Topic 751, Social Security and Medicare withholding rates
- IRS Topic 560, Additional Medicare Tax – 0.9% withheld over $200,000