Montana Income Tax Calculator

Montana overhauled its income tax for the 2024 tax year, replacing a seven-bracket system with a simpler two-rate structure: most income is taxed at 4.7%, and income above a threshold is taxed at 5.9%. This calculator applies those rates after Montana’s standard deduction to estimate your state income tax liability.

Why Montana’s 2024 reform matters

Before 2024, Montana had a graduated seven-bracket system with rates running up to 6.75%. The 2024 reform cut rates and condensed those brackets to just two. For most Montana earners the change lowered their state tax burden: the top rate dropped from 6.75% to 5.9%, and the 4.7% lower bracket now captures a large share of a typical middle-income salary. The reform also tied state taxable income closely to the federal calculation, so you no longer need a separate Montana-specific deduction schedule for most situations.

The three-step method

The calculation mirrors the Montana 2024 method:

1. Start from taxable income. Montana now ties state taxable income closely to your federal taxable income.
2. Subtract the standard deduction. Montana grants a standard deduction that mirrors the federal one (about $15,000 single, $30,000 married-jointly for 2024). If you itemize and your deductions exceed the standard amount, enter the itemized total instead.
3. Apply the two rates. The first slice of taxable income up to the bracket threshold is taxed at 4.7%; everything above it is taxed at 5.9%. The threshold is roughly $20,500 for single filers and $41,000 for married filing jointly.

The result shows your estimated Montana state income tax plus both the effective rate (total tax divided by gross income) and the marginal rate (the rate on your next dollar).

The parameters the tool applies, by filing status:

Both the deduction (which tracks the federal standard deduction) and the bracket threshold are inflation-adjusted, so expect the exact figures to drift upward each tax year — the structure, not the dollar amounts, is the durable part.

Worked example

A single filer with $60,000 of gross income:

1. Subtract the ~$15,000 standard deduction → $45,000 of Montana taxable income.
2. First $20,500 taxed at 4.7% → $963.50
3. Remaining $24,500 taxed at 5.9% → $1,445.50
4. Total state tax: ~$2,409 — an effective rate of about 4.0% on gross income.

Compare that to the pre-2024 regime where the same income would have climbed through multiple brackets up to 5.9–6.5%, often resulting in a higher bill.

The no-sales-tax context

Montana’s income tax carries more of the state’s revenue load than most states’ income taxes do, because Montana is one of the handful of US states with no general sales tax. The practical upshot for household budgeting: the number this calculator produces is close to your entire state-level tax exposure on ordinary spending and earning (property tax aside). Comparing Montana’s ~4-5% effective income tax against a state with 5% income tax plus 7% sales tax on most purchases makes Montana considerably cheaper than the income-tax figure alone suggests.

No local income tax — ever

Unlike Ohio, Pennsylvania, or New York, Montana has no city or county wage tax anywhere in the state. Whether you earn your income in Billings, Missoula, Bozeman, or a remote ranch outside Great Falls, the state calculation above is the complete Montana income tax picture. No separate municipal return, no local withholding form.

Effective rate versus marginal rate

Your marginal rate is 4.7% or 5.9% — the rate on your last dollar earned. Your effective rate is always lower because the first dollars are taxed at the lower rate. For the $60,000 example above, the marginal rate is 5.9% but the effective rate is about 4.0%. Planning decisions (retirement contributions, timing of income) depend on the marginal rate; comparing your overall burden to other states uses the effective rate.

A second example makes the compression visible: a married couple with $120,000 gross takes the $30,000 deduction to reach $90,000 taxable. The first $41,000 at 4.7% is $1,927; the remaining $49,000 at 5.9% is $2,891; total $4,818, an effective rate of just 4.0% on gross — identical to the single filer’s effective rate at half the income, which is the signature of a nearly-flat two-rate system.

To see your full take-home including federal tax and FICA deductions, use the Montana Paycheck Calculator.

Sources

• Montana Department of Revenue — official brackets, thresholds, and forms
• Tax Foundation — state individual income tax rates and brackets — cross-state comparison context

Estimate only, not tax advice. Figures model the 2024 two-rate reform; thresholds and deductions are inflation-adjusted annually, and credits (EITC, elderly homeowner credit, etc.) are not modeled. Verify against the Montana Department of Revenue before filing. All math runs locally in your browser.