Your bonus is not taxed at a special rate
There is no bonus tax. Supplemental wages are ordinary income taxed at your ordinary rates. What differs is withholding — the estimate your employer sends in advance. If it over-withholds, the excess comes back at filing; if it under-withholds, you owe. The tax itself is identical either way.
Which method your employer uses
Most large payroll systems default to the flat 22% because it is simpler. The aggregate method appears more often when the bonus is paid inside a regular payroll run rather than as a separate payment. Your pay stub will show a combined gross for the period if the aggregate method was used.
Deferring the bonus into a 401(k)
Many plans allow a separate deferral election for bonuses. Sending part of it to a traditional 401(k) reduces the taxable amount immediately, still counts toward the annual limit, and sidesteps the whole withholding question for that portion. It has to be elected before the bonus is paid — usually weeks in advance.
If the withholding creates a cash problem
You cannot reclaim over-withholding mid-year directly, but you can adjust your W-4 for the remaining periods to reduce ongoing withholding and even out the year. That is legitimate and is exactly what the extra-withholding and deductions fields on the W-4 are for.
FAQ
Why was my bonus taxed at 40%?
It was not taxed at 40% — it was withheld at that rate. Under the aggregate method, payroll treats the inflated check as your normal pay and withholds accordingly. The difference between withholding and actual tax comes back as a refund.
What is the aggregate bonus method?
Your employer adds the bonus to a regular paycheck, annualises the total, calculates the tax on that annualised figure, and withholds one period's worth. It typically withholds more than the flat 22% method.
Which method is better for me?
The flat method usually leaves more cash in hand now if your marginal rate is under 22%; the aggregate method can withhold less if your income is very low. Either way the annual tax is identical — only the timing changes.
Can I avoid tax on a bonus?
Not avoid, but defer: contributing the bonus to a traditional 401(k) or HSA reduces current taxable income. You pay tax later on 401(k) withdrawals; HSA withdrawals for medical costs are never taxed.
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