Why your bonus was taxed so much
A bonus check that arrives 35% or 40% lighter feels like a special bonus tax. There isn't one. The IRS taxes a bonus exactly like salary — as ordinary income at your bracket — and the big bite on the check is withholding, an estimate collected in advance. When you file, the withholding is credited against your real tax, and any excess comes back.
Why the check looks so small
Four withholding lines stack on a bonus: 22% federal (the flat supplemental rate), 6.2% Social Security, 1.45% Medicare and your state's supplemental rate, which runs from zero to 11.70%. Social Security and Medicare are real, final taxes — there's no refund of those unless too much Social Security was withheld across multiple employers. The federal and state income tax lines are the ones that get squared up at filing time.
What a $10,000 bonus really adds to federal tax
For a single filer with only wage income and the 2026 standard deduction ($16,100), using the 2026 tax brackets from Revenue Procedure 2025-32:
| Salary | Withheld (22%) | Tax the bonus adds | Difference |
|---|---|---|---|
| $35,000 | $2,200.00 | $1,200.00 | $1,000.00 refund |
| $60,000 | $2,200.00 | $1,550.00 | $650.00 refund |
| $110,000 | $2,200.00 | $2,200.00 | $0.00 refund |
| $220,000 | $2,200.00 | $3,200.00 | $1,000.00 owed |
| $450,000 | $2,200.00 | $3,500.00 | $1,300.00 owed |
Below roughly $66,500 of salary the bonus is taxed at 12% (or partly 12%), so 22% over-withholds. Between about $66,500 and $121,800 the bonus falls in the 22% bracket and the withholding is close to exact. Above that, 24%, 32% and 35% brackets mean 22% under-withholds. Married couples filing jointly have brackets twice as wide at the bottom: the same $10,000 bonus on a $110,000 salary adds $1,200.00 to a joint return's tax.
The same logic applies to state tax
In flat-tax states — Illinois (4.95%), Pennsylvania (3.07%), Michigan (4.25%), Indiana (2.95% plus county) and others — the bonus withholding matches the real tax almost exactly. Where the supplemental rate is above most people's actual rate, such as New York's 11.70% or North Carolina's 4.09% against a 3.99% tax rate, the state line usually over-withholds and some returns as a state refund. Where it's below the top bracket (Minnesota's 6.25%, Nebraska's 3.5%), higher earners can owe.
How to avoid a surprise
- Run the calculator with your regular pay filled in: it shows the tax the bonus adds and how far withholding is from it.
- If you expect to owe, raise withholding for the rest of the year with W-4 Step 4(c), or make an estimated payment.
- If you expect a large refund and would rather have the money now, ask whether payroll can use the aggregate method only when it helps — it lowers withholding for people in the 10% and 12% brackets — or reduce withholding on later paychecks.
- A 401(k) deferral out of the bonus cuts federal (and most state) income tax at your marginal rate, not at 22%.