Idaho Bonus Tax Calculator
Data compiled and maintained by Edmond Daher · Updated 2026-08-02
Idaho bonus tax calculator
2025 brackets (2026 pending). Idaho has not published its 2026 income tax brackets yet, so figures worked out from those brackets use its 2025 ones. We update this page when the state publishes.
Wondering why your Idaho bonus shrank so much? It's withholding, a flat prepayment, not a higher rate on bonuses. Idaho adds a flat 5.3% on top of the 22% federal prepayment and FICA. Type in your salary and bonus above and the tool lines up today's withholding against your true tax, with the refund or balance due. Everything runs in your browser.
The quick take: a stand-alone Idaho bonus has a flat 22% federal tax withheld, 5.3% for Idaho, plus 7.65% FICA. Treat it as money on account. The real tax is your marginal rate, reconciled on your return; the tool above shows the gap either way.
Estimate only, not tax advice — terms.
Cross-border check: Idaho vs. Washington, Utah and Montana on a bonus
Take a $10,000 bonus for someone on $70,000 and compare Idaho with bordering Washington, Utah and Montana:
| State | Bonus method | State withheld | Total withheld |
|---|---|---|---|
| Idaho | flat 5.3% | $530 | $3,495 |
| Washington | no state income tax | $0 | $2,965 |
| Utah | aggregate (~4.45%) | $445 | $3,410 |
| Montana | flat 5% | $500 | $3,465 |
Total combines the 22% federal, the state line, and FICA. Single-filer estimates — your real income tax settles when you file.
What Idaho holds back on a $5,000, $25,000, or $100,000 bonus
For a single filer on a $70,000 salary, here's the Idaho withholding at three bonus amounts:
| Bonus | Federal | Idaho | FICA | Total | % of bonus |
|---|---|---|---|---|---|
| $5,000 | $1,100 | $265 | $383 | $1,748 | 34.9% |
| $25,000 | $5,500 | $1,325 | $1,913 | $8,738 | 34.9% |
| $100,000 | $22,000 | $5,300 | $7,650 | $34,950 | 34.9% |
The share changes because Social Security ends at the wage base; the income tax reconciles on your return either way.
How a Idaho bonus is withheld: 22% federal + a flat 5.3%
How the federal 22% works. A bonus identified separately from regular wages is withheld at a flat 22% federally (IRS Publication 15). It rises to a mandatory 37% on any bonus dollars past $1,000,000 in a year — the third bracket's rate as a default, not a bonus tax.
Idaho: a set 5.3%. Idaho applies one flat supplemental rate — 5.3% of the bonus — for state withholding (Idaho State Tax Commission).
FICA is the real tax. Social Security (6.2% to the wage base) and Medicare (1.45%, +0.9% above $200,000) are owed at the same rate they're withheld. So FICA reads identically in both columns of the calculator; only the income-tax withholding settles up at filing.
For your regular salary rather than a bonus, use the Idaho paycheck calculator.
What a $6,500 bonus really costs on a $36,000 Idaho income
Say you earn $36,000 in Idaho and your employer cuts a separate $6,500 bonus check:
- Withheld now: $1,430 federal (22%) + $345 Idaho + $497 FICA = $2,272 held back, leaving about $4,228 in hand — a 34.9% bite.
- The real bill: at filing the bonus is taxed roughly $1,125 in income tax (federal $780 + Idaho $344), with the identical $497 FICA on top.
- The gap: you over-paid income tax by roughly $650, and that returns as a refund at filing. FICA ($497) stays either way — it's a real tax.
Illustrative single-filer figures from this page's engine; your result depends on your total income and filing status.
The "Idaho bonus tax" myth, and what's really withheld
Bonuses aren't taxed differently — only withheld differently. The real tax is your ordinary marginal rate, settled on your return, not the flat 22% on the check. Under 22% (most people) the extra comes back as a refund; over 22% you owe the difference. Worked out for the $6,500 bonus here, about $650 returns as a refund. Set aside the 7.65% FICA — that part is owed for good and never refunds.
Idaho bonus tax FAQ
Does a bonus push my Idaho 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.
Are bonuses taxed at a higher rate in Idaho?
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.
Will I get some of my Idaho bonus withholding back?
Often, yes — if your true marginal rate is below the 22% withheld, the difference refunds at filing; above 22%, you owe it. FICA is a true tax and never refunds.
What rate does Idaho withhold on a bonus in 2026?
Idaho's supplemental withholding is 5.3%, added to the flat 22% federal prepayment (37% on bonus pay over $1,000,000/yr) and 7.65% FICA. Only the income-tax portion is a prepayment; it trues up at your real rate.
Bonus tax calculators near Idaho
Idaho paycheck calculator · all state bonus tax calculators →
Sources
- IRS Publication 15 (2026) — Supplemental Wages (flat 22% / 37% above $1M)
- Idaho supplemental rate: Idaho State Tax Commission (optional flat 5.3%, HB 40)