Filing and paying Montana income tax
- Return
- Form 2, due April 15.
- Withholding
- From 2026 employers use a method built on the federal standard deduction, with the revised Form MW-4.
To see how Montana sits against every other state on top rate, bracket count and standard deduction, see state income tax rates for 2026 — all 51 jurisdictions in one sortable table.
How Montana Income Tax Compares to Neighboring States
Total income tax (federal + state) on a $100,000 annual salary in 2026, single filer using the standard deduction:
| State | State Tax | Total Income Tax | vs. Montana |
|---|---|---|---|
| Montana (here) | $4,289 | $17,459 | — |
| Idaho | $4,202 | $17,372 | -$87 |
| Wyoming | $0 | $13,170 | -$4,289 |
| South Dakota | $0 | $13,170 | -$4,289 |
| North Dakota | $669 | $13,839 | -$3,620 |
A negative "vs." figure means that state collects less total income tax than Montana. Federal portion is identical across states; only state tax varies.
Frequently Asked Questions
What is the Montana state income tax rate for 2026?
Montana state income tax for 2026 ranges from 4.7% on the lowest bracket to 5.65% on income above $47,500 (single filer). The top rate starts low enough that most full-time earners pay it on part of their income.
How much income tax will I pay in Montana on a $100,000 salary?
For a single filer earning $100,000 in Montana in 2026, expect approximately $13,170 in federal income tax and $4,289 in Montana state income tax — for a total income tax of about $17,459, an effective rate of 17.5%. This excludes FICA (Social Security and Medicare), which adds roughly 7.65% on top.
What are Montana's income tax rates for 2026?
4.7% on taxable income up to $47,500 for single filers ($95,000 joint) and 5.65% above.
Will Montana's rates change in 2027?
Yes. Under HB 337 the 4.7% rate covers up to $65,000 single ($130,000 joint) and the top rate is 5.4%.
Does Montana tax Social Security?
Yes, to the same extent as the federal return, but taxpayers 65 or older get a $5,500 subtraction.
For the preferential federal rates on long-term gains, see the Capital Gains Tax Calculator. For the federal brackets, standard deduction, and Social Security wage base that sit underneath this state calculation, see 2026 Tax Calculators.