Montana Property Tax Calculator (Assessed Value & Millage Rates)

At an average effective rate of 0.69%, Montana ranks #33 among the 50 states, putting it below the national median. That is noticeably below the national average of roughly 1.0%, based on the average effective rate across all 50 states. Compared with the rest of the West, which averages roughly 0.71%, Montana lands above its neighbors.

As in most of the West, property tax revenue in Montana funds local school districts, county services, and municipal budgets rather than flowing through a state-level general fund, so the rate is effectively set locally even though the average is reported statewide.

Assessments are handled at the county level in Montana, where local appraisers periodically revalue residential and commercial parcels and apply the applicable millage rates; homestead exemptions and formal appeals remain the main levers available to individual owners looking to manage the bill, alongside any local bond measures voters approve along the way.

Montana has no general sales tax, which puts unusual weight on property. Taxable value is a small statutory percentage of market value, and the state reappraises residential property on a fixed cycle that resets every home in the state at once, so bills move in steps rather than drifting.

None of that detail is asked for here. This calculator works one level up, applying Montana's average effective property tax rate of 0.69% to the value you enter. That rate is the ratio of property taxes actually paid to home value across the state, so the assessment ratios, caps, and exemptions described above are already baked into it.

What the calculator itself does is shorter than any of that, and it is worth being exact about, because this family of pages has previously described work the engine does not perform. There is no assessed-value conversion in the code, no millage lookup, and no reassessment logic of any kind:

1. Read the value you entered in the market value field.
2. Subtract the exemption you entered, and floor the result at zero. This is the only adjustment made to the base.
3. Multiply by the single stored effective rate of 0.69%. One number, read from the state property tax table, applied once. There is no bracket, no class ratio and no local rate.
4. Divide the annual figure by twelve for the escrow output, rounded to the cent.
5. Build the twelve-row schedule by multiplying the value you entered by the row number and dividing by six, then applying the same 0.69% to each tier.

Using this calculator's baseline inputs: a $400,000 home in Montana, taxed at the state's 0.69% average effective rate (rank #33 of 50 states).

1. Start with the assessed value. The home is assessed at its full $400,000.00 market value, with no homestead exemption applied in this baseline scenario.
2. Apply the effective rate. $400,000.00 × 0.69% = $2,760.00 in annual property tax, Montana's statewide average effective rate.
3. Convert to a monthly escrow. Lenders typically collect property tax in twelve equal installments alongside principal and interest: $2,760.00 ÷ 12 = $230.00 per month.
4. Check the monthly and the per-thousand figures. The escrow output is $230.00 a month, and each additional $1,000 of market value adds $6.90 a year to the bill.

At 0.69%, Montana lands roughly in the middle nationally, ranking #33 of 50 states. That is a moderate but still material carrying cost for homeowners.

The rate never changes, so the sweep is a straight line and every question about it has an arithmetic answer.

Each additional $1,000 of market value costs $6.90 a year. Raising the entry from $400,000 to $401,000 moves the annual tax from $2,760.00 to $2,766.90, and the same step applies at $100,000 or at $5,000,000. Per $10,000 of value the figure is $69.00.

The schedule row by row. Row 1 prices a $66,666.67 tier at $460.00 a year. Row 6 is your own entry, $400,000 at $2,760.00. Row 12 is $800,000 at $5,520.00, exactly twelve times row 1. The third column is the monthly figure for that row rather than a cumulative total, so nothing in this table accumulates.

The exemption walk. With no exemption the tax is $2,760.00 a year and $230.00 a month. Enter a $25,000 exemption and it becomes $2,587.50 and $215.63, a saving of $172.50 a year. Enter the field's $200,000 maximum against the $400,000 default and the tax falls to $1,380.00. The relationship is exactly linear, because the exemption comes off the base before the single rate is applied: every $1,000 of exemption is worth the same $6.90 that $1,000 of value costs.

Where a $25,000 entry lands. The twelve-row schedule nets the exemption off each row's value before applying the 0.69% rate, exactly as the headline does. Enter $400,000 with a $25,000 exemption and the headline reads $2,587.50 against the $2,760.00 the page returns with the field at zero, a saving of $172.50 a year, and row 6 of the schedule reads $2,587.50 as well. Row 1 moves from $460.00 to $287.50 under the same entry. The two outputs answer the same question at the same exemption level, so the table can be read straight down against the result above it.

The reverse question: how much house before the annual bill reaches $5,000? At $724,637 of market value the tax reaches $5,000.00, or $416.67 a month. Nothing statutory happens at that point; it is simply where 0.69% of the value crosses the round number, and the escrow line crosses $416.67.

Right method against wrong method, priced. The input wants market value, because the stored 0.69% is an effective rate: taxes actually paid divided by home value across the state. If you instead enter the assessed or taxable figure printed on your notice, and that figure is a fraction of market value, the result is understated in the same proportion. Entering $100,000 where the market value is $400,000 returns $690.00 instead of $2,760.00, understating the annual bill by the difference. This is the single most common way to get a wrong answer out of this page, and no validation catches it because $100,000 is a perfectly plausible entry.

• The engine applies one statewide effective rate and nothing else. There is no county or municipal millage lookup, no assessment ratio, no classification, no cap or abatement logic, and no reassessment modelling anywhere in the code path. A single stored rate of 0.69% multiplies the value you enter.
• The exemption field is a flat dollar reduction of the base. It does not know which exemption you mean, tests no eligibility, and applies no per-programme cap beyond the field's own $200,000 maximum.
• The exemption field is a flat dollar subtraction with no eligibility test. Whatever you type is removed from the base before the 0.69% rate is applied, and the engine treats a general homestead, a senior freeze and a disabled-veteran exemption as the same number. A $25,000 entry returns $2,587.50 on a $400,000 home, $50,000 returns $2,415.00 and $100,000 returns $2,070.00; no step of that sweep asks whether the amount is one you actually qualify for, and no per-programme cap is enforced beyond the field's own maximum.
• Specific hyper-local county and municipal millage district variations within Montana.
• Rural Special Improvement District (RSID) and Special Improvement District (SID) assessments. Montana property owners, particularly in rural subdivisions, can petition the county to form an RSID or a city to form a SID to fund roads, water, sewer lines, or street lighting, repaid through an annual assessment on the property tax bill on top of the base county millage.
• Commercial vs residential assessment classification differentials.
• Property tax appeal reductions or localized board of equalization adjustments.

• Confusing Market Fair Value with Assessed Basis: Some jurisdictions assess property at fractional ratios rather than 100% of market value.
• Failing to File Homestead Paperwork: Homestead exemptions are rarely automatic; homeowners must file timely paperwork with the county appraisal district.
• Underestimating Post-Sale Supplemental Assessments: Purchasing a newly constructed or reassessed property often triggers catch-up supplemental tax bills.
• Ignoring Property Tax Appeal Windows: Missing the annual 30-to-60 day statutory protest window forfeits the right to challenge over-assessed property values for that tax year.

• U.S. Census Bureau: American Community Survey (ACS) Real Estate Assessment Benchmark Data. census.gov/programs-surveys/acs
• Montana Department of Revenue, Property Assessment Division: Assessment Ratio Manuals. mtrevenue.gov