What is the property tax rate in Boulder County?

The combined effective property tax rate in Boulder County, Colorado is approximately 0.55%.

Boulder County Property Tax Calculator (2026) — Colorado Property Tax Almanac

Property Tax in Boulder County, 2026

A calculator and field guide for Boulder-area homeowners — and for anyone considering a move to Boulder County — including Colorado's 6.7% residential assessment ratio with the 10%/$700K reduction (HB 24B-1001), the SB 24-233 5.5% annual revenue growth cap, TABOR's voter approval requirement for tax rate increases, and the Senior Homestead Exemption + Disabled Veterans Exemption (each 50% of first $200K of actual value).

Boulder County, home to Boulder and 330k Coloradans, operates under Colorado's complex multi-rate residential property tax system. Colorado uses a residential assessment ratio of 6.7% for local government levies (with a 10% reduction on the first $700,000 of actual value under HB 24B-1001) and 7.05% for school district levies. Tax = (Actual Value − Reduction) × AR × Mill Levy / 1,000. The Taxpayer's Bill of Rights (TABOR, passed 1992) requires voter approval for any tax rate increase or new tax.

How the bill is built

Colorado's property tax calculation has multiple steps. Step 1: Actual Value. The Boulder County Assessor determines actual value (= fair market value) every other year (odd years). Step 2: Apply reduction. For 2026, the lesser of 10% of actual value, $70,000 (inflation-adjusted), or whatever leaves AV ≥ $1,000 is subtracted. Step 3: Apply assessment ratio. The reduced actual value is multiplied by 6.7% (local govt) or 7.05% (school) to get assessed value (AV). Step 4: Apply mill levy. Tax = AV × mill levy ÷ 1,000. Boulder's combined effective rate is approximately 0.55% of actual value. Step 5: Apply Senior or Veterans Exemption. Senior Homestead OR Disabled Veterans Exemption (not both) provides 50% reduction on first $200,000 of actual value (~$100K AV reduction).

HB 24B-1001 (Aug 2024 special session) is why your Colorado tax bill might still be rising. Despite lowering the residential assessment ratio from 6.95% to 6.7-6.8% and adding the 10%/$700K reduction, many Colorado homeowners are seeing 20-40% bill increases for the 2026 tax year — driven by the 2024 reassessment cycle catching up to several years of market value growth, plus new voter-approved mill levy increases and bond debt service. The bill effectively limits future increases but does not roll back the 2024 reassessment surge. Senate Bill 24-233 caps non-school local government revenue growth at 5.5% per year going forward.

TABOR (1992) requires voter approval for tax rate increases. The Taxpayer's Bill of Rights, codified in the Colorado Constitution, requires voter approval for: (1) new taxes, (2) tax rate increases, (3) tax policy changes resulting in net revenue gain, and (4) extension of expiring taxes. TABOR does NOT directly cap property values from rising — which is why HB 24B-1001 was needed to provide assessment-based relief. Voters can (and frequently do) "de-Bruce" their local government — voting to allow excess revenue retention beyond TABOR limits, which is why some CO local governments grow faster than others.

The Senior Homestead Exemption requires 10 consecutive years of occupancy. Established by Article X §3.5 of the Colorado Constitution (2000), the Senior Homestead Exemption provides 50% reduction on the first $200,000 of actual value (~$100K AV reduction) for owner-occupants 65+ who have owned and occupied the property for 10 consecutive years prior to January 1. The 10-year requirement is unusual — it excludes recent transplants regardless of total years lived in Colorado. The Senior Primary Residence Classification (HB 24B-1001, 2025-2026 only) provides "portability" for seniors who previously qualified but moved to a new primary residence within Colorado.

2026 Boulder County rate breakdown (effective dollars per $100 of actual value (post 6.7% AR), Boulder district)

Taxing entity	Rate
Combined mill levy (~82 mills × 6.7% AR effective ~$0.55 / $100 AV)	0.5500
Combined total	0.5500

As of April 26, 2026 · From Boulder County Assessor.

Note: Boulder County is **the iconic Colorado university town and outdoor lifestyle anchor** — Boulder (~108K) is home to the University of Colorado Boulder (~36K students, the flagship of the CU system) and is one of the most-quoted "best places to live" cities in the United States in lifestyle and outdoor recreation rankings. The county also includes Longmont (~100K, more affordable and family-oriented), Louisville and Lafayette (suburban/commuter), and Erie (partially in Weld County). Boulder is famously progressive in environmental, urban planning, and cannabis policy — Boulder voters were among the first US cities to pass strict greenhouse gas reduction targets.

Note: Boulder County effective property tax rates run approximately 0.55% — moderate by Colorado standards. Combined mill levies: Boulder (city) ~82 mills, Longmont ~80 mills, Lafayette ~85 mills, Louisville ~80 mills. Median home values around $735K combined with the moderate effective rate produce median annual bills around $4,043 — among the higher in Colorado, reflecting Boulder's premium home values. Boulder Valley School District (covering Boulder, Lafayette, Louisville, Superior) is among the highest-rated in Colorado.

Note: For relocation buyers: Boulder County is the **premium Colorado lifestyle** option — strong job market (CU, federal labs at NIST/NCAR/NOAA, Google Boulder, IBM Boulder, Ball Aerospace), exceptional outdoor recreation (Flatirons, Chautauqua Park, Boulder Open Space — 45,000+ acres of preserved land surrounding the city), and walkable Boulder downtown. The trade-off: very high home prices (Boulder city median $1M+, suburban communities $750K-$900K), strict growth controls (the Boulder Blue Line preserves mountain views by limiting development above ~5,750 ft elevation), and an unusual tenants-rights/short-term-rental regulatory environment.

Deductions and exemptions for 2026

Colorado homeowner property tax relief is concentrated in four mechanisms: (1) HB 24B-1001's 10% reduction on the first $700,000 of actual value (universal — applies to ALL residential property, not income-tested), (2) the Senior Homestead Exemption (50% of first $200K of actual value for owner-occupants 65+ with 10-year occupancy), (3) the Disabled Veterans Property Tax Exemption (same 50%/$200K for 100% P&T or TDIU veterans), and (4) the Gold Star Spouse Exemption (same benefit for surviving spouses of service members killed in line of duty).

HB 24B-1001 Residential Reduction (universal)

For 2026, the lesser of 10% of actual value, $70,000 (inflation-adjusted starting 2026), or whatever leaves AV ≥ $1,000 is subtracted from actual value before applying the 6.7% local government residential assessment ratio. This is automatic — applies to every residential property without application. The reduction is the largest single piece of relief introduced in Colorado's 2024 property tax reforms (alongside SB 24-233's 5.5% revenue growth cap on non-school local government).

Senior Homestead Exemption (Article X §3.5)

Colorado's constitutional Senior Homestead Exemption provides 50% reduction on the first $200,000 of actual value (~$100K AV reduction) for owner-occupants who are: (a) 65+ as of January 1, AND (b) have owned and occupied the property as primary residence for the 10 consecutive years preceding January 1. The 10-year occupancy requirement is unusual and excludes recent transplants. Surviving spouses of qualifying seniors retain the exemption. Apply with your county assessor by July 15. Once approved, the exemption remains in effect — no annual reapplication. The state reimburses local treasurers for lost revenue (when the legislature funds the program — historically funded since reinstatement in 2012).

Disabled Veterans Exemption (Referendum E, 2006)

Colorado's Disabled Veterans Property Tax Exemption (Article X §3.5, expanded 2006) provides 50% reduction on the first $200,000 of actual value (~$100K AV reduction) for veterans rated 100% Permanent and Total disabled by the VA OR Total Disability Individual Unemployability (TDIU). No age requirement, no income limit, no residency requirement. Surviving spouses retain the exemption. The Gold Star Spouse Exemption (Amendment E, 2022) extends the same benefit to surviving spouses of service members killed in the line of duty. Apply with the Colorado Division of Veterans Affairs by July 1. Long Form (first-time application) requires VA documentation; subsequent years use Short Form.

Senior Primary Residence Classification (2025-2026 only)

HB 24B-1001 created a temporary "portability" classification (in effect for property tax years 2025 and 2026 only) for seniors who previously qualified for the Senior Homestead Exemption but moved to a new primary residence — the 10-year occupancy clock effectively transfers to the new property. Apply for the Qualified Senior Primary Residence Classification with your county assessor.

Appealing your assessment

Colorado property tax appeals run through the County Board of Assessment Appeals. Homeowners file a Notice of Protest with the County Assessor between May 1 and June 8 of the reassessment year (Colorado reassesses every odd-numbered year). The Assessor responds with a decision; if denied, homeowners can appeal to the County Board of Equalization (BOE) by July 15. BOE decisions can be appealed to the Colorado Board of Assessment Appeals (BAA) in Denver within 30 days; from there to District Court within 30 days of BAA's decision. The 2024 reassessment surge created substantial appeal volume — approximately 20% of Colorado homeowners appealed their 2024 valuations.

Cities and towns in Boulder County

Boulder County contains 6 incorporated municipalities, ranging from Boulder to the smallest village. Search volume for property tax is often city-specific, so here is the complete list — with population from the 2020 US Census, rounded to the nearest 100.

Data: US Census Bureau, 2020 Decennial Census. Populations rounded. Cities marked as "split" straddle a county border — the portion inside Boulder County is subject to Boulder County's tax rolls, while the portion outside is subject to the adjacent county's.

City or town	Type	Population (2020)
Boulder County seat	city	108,300
Longmont	city	99,800
Erie Split	town	33,700
Lafayette	city	30,700
Louisville	city	21,100
Superior	town	13,200

About city-level property tax rates: The rate breakdown and calculator on this page reflect the Boulder tax district. Other cities in Boulder County may pay into different school districts, city rates, and special districts — so their combined rates can differ, sometimes substantially. Always verify the specific rates for your address with the Boulder County Assessor before relying on any estimate.

Frequently asked questions

When are Colorado property taxes due?

Colorado property taxes are due in two installments: February 28/29 (first half) and June 15 (second half). Bills under $25 must be paid in full by April 30. Late payments incur 1% per month interest. Most Colorado homeowners pay through escrow via mortgage servicer. Properties sold during the tax year typically prorate the bill at closing. The Boulder Assessor office handles billing and collection.

Why did my Colorado property tax go up despite the new tax cuts?

Despite HB 24B-1001 lowering the residential assessment ratio to 6.7% and adding the 10%/$700K reduction, many Colorado homeowners are seeing 20-40% bill increases for the 2026 tax year. The reason: the 2024 reassessment cycle reflects several years of accumulated home value growth (Colorado reassesses every odd year), and the new tax cuts only partially offset the value increases. Voter-approved mill levy increases, bond debt service, and special district expansions also push bills higher. SB 24-233's 5.5% non-school revenue growth cap will limit future increases but does not roll back the 2024 valuation surge.

How do I apply for the Senior Homestead Exemption?

Colorado's Senior Homestead Exemption (50% of first $200K of actual value) requires: (a) age 65+ as of January 1, AND (b) ownership and occupancy of the property for the 10 consecutive years preceding January 1. The 10-year occupancy is unusual — recent transplants are excluded regardless of total years in Colorado. Apply with your county assessor by July 15 (some counties accept late applications until August 15 with no appeal rights). Once approved, the exemption renews automatically — no annual reapplication. The state reimburses the county treasurer for lost revenue (when the legislature funds the program — funded continuously since 2012 reinstatement).

How do I qualify for the Disabled Veterans Property Tax Exemption?

Colorado's Disabled Veterans Exemption (Referendum E, 2006) provides 50% reduction on the first $200,000 of actual value (~$100K AV reduction). Eligibility: (a) honorable discharge, AND (b) VA disability rating of 100% Permanent and Total OR Total Disability Individual Unemployability (TDIU). No age requirement, no income limit, no residency requirement. Apply with the Colorado Division of Veterans Affairs by July 1. Long Form (first-time application) requires DD-214 + VA disability certification; subsequent years use Short Form. Surviving spouses retain the exemption. Gold Star Spouses (Amendment E, 2022) qualify for the same benefit if their service member died in line of duty or from service-connected causes.

What is TABOR and how does it affect Colorado property taxes?

The Taxpayer's Bill of Rights (TABOR), passed by voters in 1992 and codified in the Colorado Constitution, requires voter approval for: (1) any new tax, (2) tax rate increases, (3) tax policy changes resulting in net revenue gain, and (4) extension of expiring taxes. TABOR does NOT directly cap property values from rising with the market — which is why HB 24B-1001 was needed to provide assessment-based relief. Voters can "de-Bruce" their local government — voting to allow excess revenue retention beyond TABOR limits. Many Colorado local governments have de-Bruced over the years, allowing them to retain revenue growth that would otherwise have been refunded under TABOR.

How do I appeal my Colorado assessment?

File a Notice of Protest with the County Assessor between May 1 and June 8 of the reassessment year (Colorado reassesses every odd-numbered year). The Assessor responds with a decision; if denied, appeal to the County Board of Equalization (BOE) by July 15. BOE decisions can be appealed to the Colorado Board of Assessment Appeals (BAA) in Denver within 30 days; from there to District Court within 30 days of BAA's decision. The 2024 reassessment cycle generated unusually high appeal volume — approximately 20% of Colorado homeowners appealed their 2024 valuations. Comparable sales evidence is the most-effective basis for appeal.

About Boulder County

Beyond the property tax — a few things you might not know about the place.

Weird fact

Boulder is home to the **most-Buddhist city in the United States by per-capita Tibetan Buddhist practice** — Naropa University (founded 1974 by Tibetan Buddhist meditation master Chögyam Trungpa Rinpoche) is the only accredited Buddhist-inspired university in the US. Boulder also hosts the Shambhala Mountain Center (north of Fort Collins, in the broader Boulder/Larimer area), the Drepung Loseling Monastery branch, and one of the largest concentrations of dharma teachers, meditation centers, and Tibetan Buddhist scholars in North America. The University of Colorado Boulder also has one of the largest religious studies and Tibetan studies programs in the US.

Hometown hero

Mork from Ork (Robin Williams character)

The fictional alien Mork from Ork (played by Robin Williams in Mork & Mindy, 1978-1982) lived at the Pine Brook Hill house in Boulder — the actual exterior shown in the show is a real Boulder residence at 1619 Pine Street. The series brought Boulder to national attention and substantially influenced Boulder's popular cultural image as a quirky, alternative, mountain-adjacent college town. The Pine Brook Hill house remains a tourist attraction; Boulder occasionally hosts Mork & Mindy themed events. Real-life Boulder residents have included Olympic athletes, Nobel laureates (CU Boulder has produced 4 Nobel laureates), and major tech entrepreneurs.

Biggest annual event

Bolder Boulder + Conference on World Affairs

The Bolder Boulder (annual, Memorial Day, since 1979) is **one of the largest 10K road races in the United States** — drawing 50,000+ runners and 100,000+ spectators along the 6.2-mile course through Boulder. The race finishes inside Folsom Field (CU's football stadium) and features international elite runners. The Conference on World Affairs (annual, April at CU Boulder, since 1948) is a 5-day intellectual conference featuring 100+ panelists discussing global issues — drawing thousands of CU students and Boulder community members.

Property Tax in Boulder County, 2026