Bonus withholding vs. year-end liability: a worked illustration
Why a $30,000 bonus might have ~$9,600 in federal income tax withholding yet still reconcile to a different annual liability when you file.
Single bonus event (illustrative)
Assume employer separates a $30,000 bonus and applies optional flat federal income tax withholding on the supplemental portion (22% commonly cited for ordinary supplemental amounts under current IRS guidance—verify for your year). State and FICA omitted for clarity; real checks include them.
| Line item | Amount |
|---|---|
| Bonus gross | $30,000 |
| Illustrative federal income tax withheld (22%) | $6,600 |
| Additional illustrative: FICA + state (not shown to scale) | — |
| Net cash if only federal flat applied | ~$23,400 |
Withholding is a timing tool
Employers must park money with the Treasury as wages are paid. On bonuses, payroll often uses flat supplemental withholding or aggregate methods. The 22% figure you hear is a withholding convention for many ordinary supplemental payments—not a Congress-created “bonus tax rate.”
When you file Form 1040, your actual federal income tax is computed on taxable income after all deductions and credits. If total withholding across base, bonus, and other income exceeded liability, you refund. If it fell short, you pay.
Why the stub feels worse than April
Stack federal flat withholding, state supplemental rules, FICA, and optional locals, and the gross-to-net on a single bonus check can look brutal. Annual reconciliation may still show a lower effective rate on all income combined—especially if you have deductions or credits that withholding tables did not know about midyear.
What to do with a large refund
A refund means you lent the Treasury money at zero interest. If bonuses repeat, consider raising W-4 allowances or extra withholding adjustments on base pay—or make estimated payments if self-employment mixes in.
What to do next
Practical next steps based on this topic.
After a large bonus, run a midyear tax projection.
- Model the bonus: Use the bonus calculator with your state.
- Revisit W-4: Tune if refunds or balances swing wildly.