Iowa Bonus Tax Calculator
Data compiled and maintained by Edmond Daher · Updated 2026-06-16
Got a bonus in Iowa? It isn't taxed at a special rate — what shrinks it is withholding. Iowa adds a flat 3.8% on top of the 22% federal prepayment and FICA. Drop your figures in to watch the payday deduction sit next to the real filing cost, plus whatever you get back or owe. Everything runs in your browser.
Quick answer: a separately paid bonus in Iowa is withheld at a flat 22% for federal income tax plus 3.8% for Iowa, plus 7.65% FICA. None of that is the final number — a bonus is taxed at your marginal rate once you file, so the calculator below estimates what comes back or is still due.
Estimate only, not tax advice — terms.
Is Iowa's a flat 3.8% bonus rate a "bonus tax"? No
A bonus doesn't trigger a different tax — just a flat withholding up front. When you file, it's folded into your income and taxed at your marginal rate through the normal brackets. Below a 22% real rate you get money back; above it, you settle the gap at filing. Worked out for the $18,000 bonus here, about $550 returns as a refund. Just the 7.65% FICA slice is a real tax you won't get back.
Bonus withholding in Iowa next to Illinois, Minnesota and Nebraska
A single filer earning $70,000 who gets a $10,000 bonus, in Iowa and neighboring Illinois, Minnesota and Nebraska:
| State | Bonus method | State withheld | Total withheld |
|---|---|---|---|
| Iowa | flat 3.8% | $380 | $3,345 |
| Illinois | aggregate (~4.95%) | $495 | $3,460 |
| Minnesota | flat 6.25% | $625 | $3,590 |
| Nebraska | flat 3.5% | $350 | $3,315 |
Totals stack federal 22%, state, and FICA for a single filer — the actual income tax lands when the return is filed.
Worked example: a $18,000 Iowa bonus at a $61,000 salary
Take a single filer in Iowa earning $61,000 who gets a $18,000 bonus on its own check:
- Withheld now: $3,960 federal (22%) + $684 Iowa + $1,377 FICA = $6,021 held back, leaving about $11,979 in hand — a 33.5% bite.
- What it actually costs: the true income tax on the bonus is about $4,094 (federal $3,410 + Iowa $684), plus the same $1,377 FICA.
- The gap: the flat 22% over-shoots your real rate by about $550, so that much is a refund later. The $1,377 FICA doesn't move — that part is owed no matter what.
Example single-filer numbers from the calculator above; your own refund or bill shifts with your total income and filing status.
Breaking down the withholding on a Iowa bonus
Where the 22% comes from. Employers may withhold a flat 22% of a separately identified bonus for federal income tax (IRS Publication 15). A mandatory 37% hits supplemental pay beyond $1,000,000 a year; neither figure is a special "bonus" rate, both are withholding defaults.
The Iowa rate: 3.8%. Iowa DOR withholding tax information has Iowa employers hold back a flat 3.8% on a separately paid bonus.
Set FICA aside as final. The 7.65% FICA bite is the tax itself — Social Security stops at the annual wage base, Medicare doesn't. That's why the calculator shows the same FICA under "withheld now" and "what it really costs" — there's nothing to refund; only the income-tax portion trues up.
Need your normal take-home instead? Try the Iowa paycheck calculator.
Iowa bonus withholding at $5,000, $25,000 and $100,000
Three bonuses — $5,000, $25,000, $100,000 — and what Iowa withholds from each on a $70,000 salary:
| Bonus | Federal | Iowa | FICA | Total | % of bonus |
|---|---|---|---|---|---|
| $5,000 | $1,100 | $190 | $383 | $1,673 | 33.5% |
| $25,000 | $5,500 | $950 | $1,913 | $8,363 | 33.5% |
| $100,000 | $22,000 | $3,800 | $7,650 | $33,450 | 33.5% |
The share changes because Social Security ends at the wage base; the income tax reconciles on your return either way.
Iowa bonus tax FAQ
How much is withheld from a bonus in Iowa for 2026?
On a separately paid bonus, Iowa takes 3.8%, the federal side takes a flat 22% (37% beyond $1,000,000/yr), and FICA takes 7.65%. Those are withholding rates that settle up when you file — not a final tax.
Why might I owe tax on my Iowa bonus at filing?
Because 22% is only a prepayment. If your true marginal rate is above 22% (high earners), the flat withholding falls short and you owe the rest; below 22%, you're over-withheld and get money back.
Are bonuses taxed at a higher rate in Iowa?
No. A bonus is ordinary income taxed at your normal marginal rate when you file; the flat 22% withheld is a prepayment, not a tax rate.
Does a bonus push my Iowa income into a higher bracket?
No. Brackets are marginal — only the dollars above each threshold are taxed higher. A bonus never re-taxes income you already earned.
Bonus tax calculators near Iowa
Iowa paycheck calculator · all state bonus tax calculators →
Sources
- IRS Publication 15 (2026) — Supplemental Wages (flat 22% / 37% above $1M)
- Iowa supplemental rate: Iowa DOR withholding tax information (flat 3.8%, ties to 2026 flat income tax); corroborated by Netchex