Montana Bonus Tax Calculator
Data compiled and maintained by Edmond Daher · Updated 2026-08-02
Montana bonus tax calculator
That big bite out of a Montana bonus is withholding at work — a prepayment, not a special bonus tax. Montana adds a flat 5% on top of the 22% federal prepayment and FICA. Enter your numbers to see what's held back now beside what the bonus will really cost when you file, and your refund or amount owed. Everything runs in your browser.
Quick answer: a separately paid bonus in Montana is withheld at a flat 22% for federal income tax plus 5% for Montana, 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.
Montana bonus withholding, piece by piece
How the federal 22% works. A bonus identified separately from regular wages is withheld at a flat 22% federally (IRS Publication 15). Bonus dollars over $1,000,000 in the year switch to a mandatory 37%; below that it's a flat 22% prepayment tied to the third bracket.
Montana's 5% supplemental rate. When a bonus is paid on its own, Montana DOR Publication 1 sets a flat 5% of it for Montana withholding.
The 7.65% is real. FICA — Social Security up to the wage base, plus 1.45% Medicare (and 0.9% more above $200,000) — is owed at exactly the rate it's withheld. Neither piece refunds at filing, so both columns of the tool show it unchanged; the income-tax withholding is the only part that trues up.
For everyday pay instead of a bonus, the Montana paycheck calculator is the tool to use.
Three bonus sizes in Montana: $5,000, $25,000 and $100,000 withheld
For a single filer on a $70,000 salary, here's the Montana withholding at three bonus amounts:
| Bonus | Federal | Montana | FICA | Total | % of bonus |
|---|---|---|---|---|---|
| $5,000 | $1,100 | $250 | $383 | $1,733 | 34.6% |
| $25,000 | $5,500 | $1,250 | $1,913 | $8,663 | 34.6% |
| $100,000 | $22,000 | $5,000 | $7,650 | $34,650 | 34.6% |
Watch the percentage fall once Social Security maxes out; the income-tax slice trues up when you file regardless.
The "Montana bonus tax" myth, and what's really withheld
Think of the flat rate as a deposit, not a bill. A bonus is taxed like any wages — at your marginal rate when the year's income runs through the brackets — and the 22% is only how it's withheld. If your real rate sits under 22%, the surplus refunds; if it runs above, you cover the shortfall. Worked out for the $24,000 bonus here, about $2,472 returns as a refund. Set aside the 7.65% FICA — that part is owed for good and never refunds.
Cross-border check: Montana vs. Idaho, Wyoming and North Dakota on a bonus
The same $10,000 bonus and $70,000 salary, in Montana and its neighbors Idaho, Wyoming and North Dakota:
| State | Bonus method | State withheld | Total withheld |
|---|---|---|---|
| Montana | flat 5% | $500 | $3,465 |
| Idaho | flat 5.3% | $530 | $3,495 |
| Wyoming | no state income tax | $0 | $2,965 |
| North Dakota | flat 1.5% | $150 | $3,115 |
Total combines the 22% federal, the state line, and FICA. Single-filer estimates — your real income tax settles when you file.
A $24,000 bonus on a $36,000 Montana salary: withheld vs. actually owed
Say you earn $36,000 in Montana and your employer cuts a separate $24,000 bonus check:
- Off the top: $8,316 disappears at payday — $5,280 federal, $1,200 Montana, and $1,836 FICA — so roughly $15,684 actually reaches you, a 34.6% cut.
- What it actually costs: the true income tax on the bonus is about $4,008 (federal $2,880 + Montana $1,128), plus the same $1,836 FICA.
- The gap: you over-paid income tax by roughly $2,472, and that returns as a refund at filing. Either way, the $1,836 FICA is final and won't come back.
Illustrative single-filer figures from this page's engine; your result depends on your total income and filing status.
Montana bonus tax FAQ
Is there a special bonus tax rate in Montana?
No. The 22% federal and the state supplemental rate are withholding defaults, not rates that apply only to bonuses. Your real tax is your ordinary marginal rate.
Does a bonus push my Montana 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.
How much is withheld from a bonus in Montana for 2026?
On a separately paid bonus, Montana takes 5%, 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.
Do I get a refund on my Montana bonus?
If 22% was more than your real rate, yes — the over-withheld income tax returns at filing. If your marginal rate tops 22%, you owe the shortfall. FICA doesn't come back either way.
Bonus tax calculators near Montana
Montana paycheck calculator · all state bonus tax calculators →
Sources
- IRS Publication 15 (2026) — Supplemental Wages (flat 22% / 37% above $1M)
- Montana supplemental rate: Montana DOR Publication 1 (2026): 'a flat 5 percent of the supplemental wage'