Montana Property Tax Calculator

How this calculator works

Montana property tax is governed by Title 15, Chapter 7 of the Montana Code Annotated (MCA) — the property-assessment chapter — together with the classification statutes in Title 15, Chapter 6. Three structural features distinguish Montana from most other states: a statutory class-based assessment system with twelve classes (MCA § 15-6-101), a Class 4 residential rate of 1.35% (MCA § 15-6-134 — recently reduced from 1.89%), and a 2-year reappraisal cycle (MCA § 15-7-111).

The math is a clean three-step pipeline:

• market value × 1.35% (Class 4 residential rate, § 15-6-134) = taxable value
• taxable value × total mill levy / 1000 = annual property tax
• minus any PTAP adjustment under § 15-6-301 if the owner qualifies

Everything else is determining the right mill levy and whether the owner qualifies for the Property Tax Assistance Program.

The Class 4 1.35% rate — and why it changed

Montana sorts every parcel into one of twelve property classes under § 15-6-101. Residential real property — owner-occupied homes, single-family rentals, mobile homes on owned land — sits in Class 4. The 2025–2026 statewide taxable rate is 1.35% of market value (§ 15-6-134).

This is a recent and material change. The rate was previously 1.89%. The reduction enacted during the 2023–2024 legislative cycle (with HB 231 (2024) as the major rebalancing vehicle) was designed to offset reappraisal-driven valuation increases that flowed through the 2-year reappraisal cycle.

What happened:

• The 2023 reappraisal cycle captured the 2020–2022 housing boom and produced sharp residential market-value increases — roughly 40%–60% in fast-appreciating counties (Gallatin, Flathead, Missoula).
• At the prior 1.89% rate, those increases would have flowed straight into residential bills.
• Commercial property — also in Class 4 but appreciating more slowly — would have absorbed a smaller share.
• HB 231 (2024) rebalanced within Class 4: cutting the statewide residential rate to 1.35% while keeping the commercial portion of Class 4 closer to the prior 1.89% figure.

The structural intent was to hold the residential share of total state property-tax revenue roughly constant despite residential values rising faster than commercial values. Mill levies set by local jurisdictions still vary independently, so the binding residential bill depends on both the statewide 1.35% rate AND the local mill levy.

Mill levies — how local rates work

A mill is 1/1000th of a dollar, or 0.1% of taxable value. The total mill levy on a parcel is the sum of every overlapping taxing jurisdiction's levy:

• County general (~150–250 mills)
• County road (~50–80 mills)
• County library (~10–20 mills)
• School district (~200–300 mills, varies sharply by district)
• City (~80–150 mills if inside incorporated city limits)
• Special districts (fire, water, sewer, rural improvement; 10–50 mills each)

Typical residential parcel totals: 500–900 mills depending on county, school district, and city status.

Common total mill levies by county

Combined total levies (county + school + city + special districts) for 2024–2025 on residential primary residences:

| County | Total mill levy | $400K home tax | | --- | --- | --- | | Flathead (Kalispell) | 590 mills | $3,186 | | Ravalli (Hamilton) | 560 mills | $3,024 | | Gallatin (Bozeman) | 600 mills | $3,240 | | Yellowstone (Billings) | 650 mills | $3,510 | | Lewis & Clark (Helena) | 680 mills | $3,672 | | Silver Bow (Butte) | 700 mills | $3,780 | | Missoula | 720 mills | $3,888 | | Cascade (Great Falls) | 740 mills | $3,996 | | Rural / other (typical) | 550 mills | $2,970 |

Pull the binding total levy for the specific parcel from the county treasurer's annual tax notice. The levy varies block-by-block based on which school district, city limits, and special districts overlap the parcel.

The Property Tax Assistance Program (PTAP) — § 15-6-301

PTAP is Montana's primary property-tax relief program for low-income seniors and disabled owners. Unlike a homestead exemption (which reduces taxable value by a flat amount), PTAP reduces the assessment rate itself — the 1.35% Class 4 figure is cut to 30%, 50%, or 80% of the standard rate depending on income bracket.

To qualify under § 15-6-301 the owner must meet ALL of:

• Age 62 or older OR disabled (Social Security disability determination or equivalent)
• The property is the owner-occupied primary residence
• Adjusted gross income falls within one of the PTAP brackets

Single-filer brackets (married-filing-jointly brackets are typically higher; refresh annually with the Montana Department of Revenue):

| Bracket | Income (single) | Effective rate | Reduction | | --- | --- | --- | --- | | 1 (deepest) | ≤ $14,000 | 0.405% (30% of 1.35%) | 70% off | | 2 (middle) | ≤ $19,000 | 0.675% (50% of 1.35%) | 50% off | | 3 (smallest) | ≤ $26,000 | 1.080% (80% of 1.35%) | 20% off | | Above | > $26,000 | 1.35% | No PTAP |

Critically, the PTAP rate reduction applies only to the first $350,000 of market value. Any value above the cap is taxed at the standard 1.35% rate. The cap creates a hard transition for higher-value homes.

A worked example — $400,000 Billings home, age 45

A $400,000 home in Billings (Yellowstone County). Owner is 45, household income $90,000. Yellowstone's total mill levy is 650 mills (0.650).

• Market value: $400,000
• Class 4 assessment: $400,000 × 1.35% = $5,400 taxable value
• PTAP: not applicable (under 62, income above bracket 3 anyway)
• Annual tax: $5,400 × 0.650 = $3,510
• Effective rate: 0.88% of market value

That's the standard Montana residential bill — clean three-step math, no PTAP adjustment.

A worked example — same home, age 70, $12,000 income (PTAP Bracket 1)

Same $400,000 Billings home. Owner is now 70 years old, household income $12,000. Qualifies for PTAP Bracket 1 (the deepest reduction).

• Market value: $400,000
• PTAP-eligible portion: $350,000 (capped)
• Above-cap portion: $50,000
• PTAP-portion taxable: $350,000 × 0.405% (30% of 1.35%) = $1,417.50
• Above-cap taxable: $50,000 × 1.35% = $675
• Total taxable value: $2,092.50
• Annual tax: $2,092.50 × 0.650 = $1,360
• Annual savings vs the no-PTAP baseline: $3,510 − $1,360 = $2,150

The PTAP Bracket 1 senior pays roughly $2,150 less annually than a non-PTAP owner on the same home. The reduction comes from the rate cut, not from a fixed-dollar exemption — which means it scales with the home value (up to the $350K cap).

A worked example — $500,000 Bozeman home, age 70, $18,000 income (PTAP Bracket 2)

A $500,000 home in Bozeman (Gallatin County). Owner is 70, household income $18,000. Qualifies for PTAP Bracket 2 (the middle bracket). Gallatin's total mill levy is 600 mills.

• Market value: $500,000
• PTAP-eligible portion: $350,000 (capped)
• Above-cap portion: $150,000
• PTAP-portion taxable: $350,000 × 0.675% (50% of 1.35%) = $2,362.50
• Above-cap taxable: $150,000 × 1.35% = $2,025
• Total taxable value: $4,387.50
• Annual tax: $4,387.50 × 0.600 = $2,633
• No-PTAP baseline tax: $500,000 × 0.0135 × 0.600 = $4,050
• Annual savings: $4,050 − $2,633 = $1,417

The $150,000 above the cap absorbs no reduction — that's the structural feature of the $350K cap. The savings stay meaningful but don't scale linearly with home value beyond the threshold.

A worked example — what HB 231 (2024) actually changed

Same $400,000 Billings home, age 45, no PTAP. Compare current and prior rates at the same 650-mill levy:

• Current (1.35%): $400,000 × 0.0135 × 0.650 = $3,510
• Prior (1.89%): $400,000 × 0.0189 × 0.650 = $4,914
• HB 231 savings: $4,914 − $3,510 = $1,404 annually

The rate reduction alone produces ~$1,400 of annual savings on a baseline Billings home. The actual post-HB 231 bill increase or decrease compared to pre-reappraisal also depends on how much the parcel's market value moved in the 2023 reappraisal — the rate reduction was sized to offset typical valuation increases, not to produce a net cut.

The 2-year reappraisal cycle — § 15-7-111

Montana reappraises real property on a 2-year cycle under § 15-7-111. All Class 4 residential parcels in the state are revalued to current market at the start of each cycle; the new market value holds for two tax years before the next cycle begins.

This creates a sawtooth pattern in individual bills:

• A sharp step-up at the start of each cycle (year 1)
• Flat year 2
• Next step-up at year 3 (start of the next cycle)

The 2023 reappraisal cycle reflected the 2020–2022 housing boom and produced the largest single-year residential value jump in recent memory in fast-appreciating counties (Gallatin, Flathead, Missoula). HB 231 (2024) modified the reappraisal mechanics to prevent the residential side of Class 4 from absorbing a disproportionate share of post-reappraisal increases relative to commercial.

Plan around the cycle. The year-1 bill of a cycle is the planning baseline; year-3 (start of the next cycle) is the next step-up.

Comparing Montana to surrounding states

Effective property-tax rates on residential primary residences across the western states:

| State | Effective rate (typical) | Why | | --- | --- | --- | | Idaho | ~0.55% | 1% assessment rate equivalent + homestead exemption | | Utah | ~0.55% | 45% primary-residence exemption | | Wyoming | ~0.60% | 9.5% assessment + low mill levies | | Montana | ~0.75%–1.00% | 1.35% Class 4 + 500–900 mills | | Washington | ~0.90% | No state income tax shifts more to property | | North Dakota | ~1.00% | 9% residential assessment rate | | South Dakota | ~1.20% | No state income tax |

Montana sits between Idaho/Wyoming/Utah (which lean heavier on sales/severance taxes) and the Dakotas/Washington (which have no state income tax and lean on property tax). The HB 231 (2024) reduction pushed Montana modestly DOWN within this band — pre-2024 the residential rate of 1.89% put Montana closer to North Dakota; the 1.35% rate moves Montana closer to Washington.

Common errors to avoid

• Treating the 1.35% rate as the bill. The 1.35% is the assessment rate, not the tax rate. Multiply market value × 1.35% to get taxable value, then multiply taxable value × mill levy / 1000 to get the bill. Skipping the mill-levy step understates the bill by roughly 50x.
• Mixing up mills and decimals. Mills are 1/1000th. A 650-mill levy is 0.650, NOT 6.50 and NOT 0.0650. The county treasurer's tax notice quotes mills; this calculator converts internally.
• Assuming PTAP gives a homestead-style fixed exemption. PTAP reduces the assessment RATE, not the taxable value. A senior in Bracket 1 on a $200K home gets a different dollar savings than the same bracket on a $400K home — the reduction scales with value up to the $350K cap.
• Forgetting the $350K PTAP cap. PTAP rate reduction applies only to the first $350,000 of market value. A $1M home gets the same dollar reduction as a $350K home in the same bracket.
• Confusing PTAP with the MDV exemption. The Disabled American Veterans (MDV) exemption under MCA § 15-6-311 is a separate, deeper reduction for veterans with 100% service-connected disability. It is NOT modeled in this calculator.
• Confusing PTAP with the Elderly Homeowner/Renter Credit. The Elderly Homeowner/Renter Credit (Form 2EC) is a Montana state INCOME-TAX credit (up to $1,150) — it appears on the income-tax return, not the property-tax bill. Separate program.
• Missing the 2-year reappraisal step-up. Bills can jump 20%–40% in a year-1 reappraisal year in fast-appreciating counties. Hold cash to cover the step-up rather than budgeting from the year-2 baseline.
• Applying late. The April 15 PTAP application deadline is firm. File the PTAP Form with the Montana Department of Revenue (not the county) and recertify annually.

Tools, not advice. Confirm the binding county and special-district mill levies with the county treasurer and confirm PTAP eligibility (and the current statutory income brackets) with the Montana Department of Revenue before relying on any result for planning purposes.