Colorado Property Tax Calculator

How this calculator works

Colorado has one of the lowest effective property-tax rates in the United States — roughly 0.45% of actual value for a typical residential parcel — but it has also become one of the most volatile statutory frameworks. The 2020 repeal of the Gallagher Amendment (Article X § 3) ended four decades of dynamic balancing between residential and commercial property and triggered a wave of legislative adjustments that has continued through every session since. This calculator implements the current 2026 framework: post-Gallagher assessment ratios under C.R.S. § 39-1-104.2, the C.R.S. § 39-3-203 senior property tax homestead exemption, and the constitutional revenue cap under TABOR (Article X § 20).

The math is clean once the ratios are known:

• actual value × assessment ratio = assessed value
• assessed value − exemption reduction = taxable assessed value
• taxable assessed value × mill levy = annual property tax

Everything else in this calculator is determining the right ratio for the property type and the right exemption, if any, for the owner.

Colorado's split assessment ratio — residential vs commercial

Colorado is one of the few states where residential and non-residential property are assessed at dramatically different ratios. Under C.R.S. § 39-1-104.2 for tax year 2026:

| Property type | Assessment ratio | | --- | --- | | Residential single-family / condo / townhouse | ~6.4% (post-2024 special-session estimate) | | Multifamily (apartments 4+ units) | 6.5% | | Commercial | 29% (statutory) | | Industrial | 29% | | Agricultural (preferential use, § 39-1-103(5)) | 21% | | Vacant land | 27.9% |

The residential 6.4% is the lowest among the 50 states. Most states assess residential at 80%–100% of market value; Colorado has been below 10% since 2017. The commercial 29% has been substantially unchanged since 1983.

The dramatic split means a $500,000 residence is assessed at $32,000 but a $500,000 commercial parcel is assessed at $145,000 — more than 4× higher. At an identical 70-mill levy, the residential parcel owes ~$2,240 in annual tax while the commercial parcel owes ~$10,150. This is the legacy of the Gallagher Amendment.

The Gallagher Amendment — and its 2020 repeal

The Gallagher Amendment, added to Article X § 3 of the Colorado Constitution in 1982, required that residential property statewide carry 45% of the total assessed value of all property in Colorado, with non-residential carrying the remaining 55%. The mechanism: the legislature adjusted the residential assessment ratio each cycle to maintain the 45/55 split. Because residential values appreciated faster than commercial over four decades, the residential ratio was ratcheted DOWN from 21% in 1983 to 7.15% by 2019 to keep the share constant.

The downside became apparent: as residential values rose, the constantly-falling residential ratio starved local governments — particularly rural counties with few commercial properties — of property-tax revenue, because the commercial 29% ratio was fixed in statute and could not absorb the shifted share. Rural school districts and special districts in agricultural counties were the hardest hit.

Voters approved Amendment B in November 2020, repealing Gallagher and freezing the assessment ratios at then-current levels. The legislature now sets the residential ratio directly under § 39-1-104.2 without the 45/55 balancing constraint.

Post-Gallagher legislative whiplash

Following Gallagher's repeal, the legislature has enacted a series of temporary residential assessment-ratio reductions to soften the property-tax impact of the 2020–2023 housing boom:

• SB21-293 (2021): temporary 2022–2023 reductions
• SB22-238 (2022): further 2023 reduction to 6.765% plus a $15,000 actual-value subtraction
• SB23-303 + Proposition HH (2023): paired with a ballot referral to retain TABOR refunds; Proposition HH FAILED at the November 2023 election
• 2024 special session — SB24B-001 and related: held the residential ratio at approximately 6.7% for tax years 2024–2025 and provided mechanisms for 2026 and beyond

The current 2026 estimate models the post-2024 ratio at approximately 6.4%. Refresh the calculator constants when the Colorado Division of Property Taxation publishes the final ratio for the tax year — the post-Gallagher framework changes nearly every legislative session.

The Senior Property Tax Homestead Exemption (§ 39-3-203)

The Senior Property Tax Homestead Exemption excludes 50% of the first $200,000 of actual value from assessment. To qualify on January 1 of the tax year the owner must meet ALL of:

• Age 65 or older
• Owned and occupied the property as their primary residence for at least 10 consecutive years
• Property is the owner's primary residence

The exemption produces an actual-value reduction of up to $100,000 (50% × $200,000), which at the 6.4% residential ratio yields an assessed-value reduction of up to $6,400. At a 70-mill combined levy, that translates to roughly $448 of annual tax savings — modest in absolute terms but a meaningful percentage reduction in a state that already has low effective property-tax rates.

The 10-year clock is strict and does not transfer between residences. Moving to a new home resets the count, even if the prior home qualified. Joint-titled owners qualify if either spouse meets both tests; the exemption is filed once with the county assessor (typically Form 15-DPT-AR) and persists so long as the owner remains the legal occupant.

Disabled-veteran extension (§ 39-3-203(1.5))

A veteran with a 100% permanent and total service-connected disability as determined by the U.S. Department of Veterans Affairs receives the same exemption with no age 65 requirement and no 10-year ownership requirement. An unremarried surviving spouse of such a veteran (including a surviving spouse of a service member killed in the line of duty) also qualifies.

The disabled-veteran extension is the single most accessible Colorado property-tax benefit for younger owners — a 35-year-old veteran with a 100% VA rating who buys a home receives the same exemption that an age-75 owner with 15 years of tenure receives. The exemption is filed via the Colorado Department of Military and Veterans Affairs (CDMVA) certification combined with the county assessor application.

TABOR — the Taxpayer's Bill of Rights

The Taxpayer's Bill of Rights (TABOR), enacted as Article X § 20 of the Colorado Constitution in 1992, caps the annual revenue growth of every state and local taxing district to inflation plus population growth and requires voter approval for any new tax, rate increase, or retention of revenue above the cap.

For property tax this means: a county or special district cannot raise its mill levy above the prior year's figure (adjusted for the inflation+population cap) without a public vote. Many Colorado districts have passed "de-Brucing" elections (named for TABOR's author, Douglas Bruce) that permit retention of revenue above the cap — typically backfilling school district or municipal budgets.

TABOR historically interacted with Gallagher to make Colorado property-tax revenue particularly constrained. Post-Gallagher (2020), TABOR's voter-approval gate remains the binding constraint on property-tax rate increases. The mill levy this calculator uses should reflect the district's voter-approved overrides where applicable.

A worked example — $500,000 Denver residence, age 45

A $500,000 Denver residence. Owner is 45, not a disabled veteran. Combined mill levy is 70 mills (representative for the front range).

• Assessment ratio: 6.4% (residential, 2026 estimate)
• Assessed value: $500,000 × 0.064 = $32,000
• Senior exemption: not applicable (under 65, not a 100% disabled veteran)
• Taxable assessed value: $32,000
• Tax owed: $32,000 × 0.070 = $2,240
• Effective rate: $2,240 / $500,000 = 0.45% of actual value

The 0.45% effective rate is dramatically below the U.S. national average (~1.1%), Texas (1.6%–2.0%), Illinois (2.0%–2.5%), and New Jersey (~2.5%). Colorado is in roughly the same band as New Mexico, Arizona, and Utah.

A worked example — same home, age 70, owned 15 years

Same $500,000 Denver residence. Owner is now 70 years old and has owned and occupied the home as primary residence for 15 years. Same 70-mill levy.

• Assessment ratio: 6.4%
• Assessed value: $500,000 × 0.064 = $32,000
• § 39-3-203 exemption applies: yes — age 65+ AND owned 10+ years
• Exemption actual-value reduction: min($500,000, $200,000) × 50% = $100,000
• Exemption assessed-value reduction: $100,000 × 0.064 = $6,400
• Taxable assessed value: $32,000 − $6,400 = $25,600
• Tax owed: $25,600 × 0.070 = $1,792
• Effective rate: $1,792 / $500,000 = 0.36% of actual value
• Annual savings vs the under-65 baseline: $2,240 − $1,792 = $448

The senior owner pays $448 less per year. Over a 10-year continuing-residence hold the cumulative savings exceed $4,500. Modest, but meaningful for fixed-income retirees in a state already at the low end of national effective rates.

A worked example — $500,000 commercial parcel

Same $500,000 actual value, this time a commercial parcel (downtown Denver retail). Same 70-mill levy.

• Assessment ratio: 29% (statutory commercial)
• Assessed value: $500,000 × 0.29 = $145,000
• Senior exemption: not applicable (commercial parcels do not qualify)
• Taxable assessed value: $145,000
• Tax owed: $145,000 × 0.070 = $10,150
• Effective rate: $10,150 / $500,000 = 2.03% of actual value

The same $500,000 of actual value owes more than 4× the residential figure. The 4.5× spread between residential (6.4%) and commercial (29%) assessment ratios is the structural feature of Colorado's property-tax system — and the reason commercial real-estate development in Colorado often relies on tax-increment financing, opportunity zones, and metropolitan-district financing to offset the assessment ratio differential.

Why Colorado lands low on effective property tax

Three structural factors drive Colorado's roughly 0.45% effective residential rate:

1. Post-Gallagher residential ratio (~6.4%) is the lowest among the 50 states. Most states assess residential at 80%–100% of market value.
2. TABOR caps annual revenue growth and prevents the compounding mill-levy increases that drive Texas and Illinois bills.
3. K-12 funding mix: Colorado funds K-12 education partly from a statewide income-tax-and-sales-tax mix rather than purely from local property tax, reducing the load on the property-tax base.

Colorado sits in a band with neighboring New Mexico (~0.6%), Arizona (~0.6%), and Utah (~0.55%); somewhat higher than Wyoming (~0.55%) and Hawaii (~0.30%, the two lowest-rate states); and substantially lower than Texas (~1.7%), Kansas (~1.4%), and Nebraska (~1.6%).

Mill levy variation by district

Colorado mill levies are assembled district-by-district. A typical residential parcel's combined mill levy includes:

• County general fund (10–20 mills)
• City or town (if incorporated, 5–15 mills)
• School district (general fund + bonded indebtedness, 25–45 mills)
• Special districts: fire protection, water, sanitation, recreation, library, hospital (5–25 mills combined)

Combined mill levies typically run 60–90 mills (= 6%–9% of assessed value). High-mill districts (90+ mills) are usually newer suburban areas with extensive metropolitan-district debt — developer-financed infrastructure that repays through a parcel-specific mill levy. Low-mill districts (50–60 mills) are typically older urban cores and rural counties without metropolitan-district debt.

Pull the binding combined mill levy for the specific parcel from the county treasurer's annual tax certification — most Colorado counties publish per-parcel breakdowns showing each district's contribution.

Common errors to avoid

• Using the wrong year's assessment ratio. The post-Gallagher residential ratio has changed nearly every legislative session — 7.15%, 6.95%, 6.765%, 6.7%, 6.4%. Pull the binding figure for the tax year from the Colorado Division of Property Taxation before relying on an exact tax number.
• Confusing actual value with assessed value. Colorado assessor records show BOTH figures; the assessment ratio applies to actual value, and the mill levy applies to assessed value (after exemptions). Multiplying actual value directly by the mill levy produces a number ~15× too high.
• Forgetting the 10-year ownership requirement. The § 39-3-203 senior exemption requires continuous ownership for the 10 years preceding January 1 of the tax year. A senior who moves loses the exemption until they accumulate another 10 years.
• Missing the disabled-veteran extension. A 100% VA disability rating bypasses the age 65 and 10-year requirements entirely. The CDMVA certification is the gating document; many qualifying veterans simply do not know the benefit exists.
• Treating the senior exemption as a tax credit. The exemption reduces assessed value, not tax owed directly. Its dollar value scales with the mill levy of the parcel; the same exemption is worth ~$448 at 70 mills and ~$575 at 90 mills.

Tools, not advice. Confirm the binding assessment ratio for the tax year, the parcel's mill levy from the county treasurer, and senior / disabled-veteran exemption eligibility with the county assessor before relying on any result for planning purposes.