Colorado Property Tax Appeal Guides
Browse source-reviewed property tax appeal guides for Colorado. County deadlines, filing methods, and available records can differ by county and tax year.
Each published guide identifies the public sources used for its deadline and filing summary. Confirm current requirements with the official filing authority before submitting anything.
How Colorado assessment appeals generally work (state framework reviewed 2026-10-05 from official Colorado sources): County assessors determine actual value, while valuation for assessment is produced by applying statutory percentages and reductions. Those percentages vary by property class and tax year; residential valuation can also differ between school-district and other local-government levies, so no single statewide parcel ratio is accurate. A property owner first protests to the County Assessor and may then petition the County Board of Equalization. After the county board, the owner may generally choose the Colorado Board of Assessment Appeals, District Court, or binding arbitration, subject to the governing statute and decision notice.
Colorado deadline framework: The standard real-property protest date depends on assessment year: June 8 for the 2026 cycle; SB26-046 changes the standard date to June 1 for cycles governed by its provisions effective January 1, 2027. A county using an authorized alternate protest and appeal procedure may have a different calendar. Read the current assessor notice and county instructions; the county-board petition and later Board of Assessment Appeals, District Court, or arbitration filings have separate deadlines tied to the notice or decision.
Local variation in Colorado: County assessors control notices, protest channels, supporting-data access, and local hearings. Counties may use standard or alternate procedures, and Denver is both a city and county. Property class, valuation year, reassessment cycle, and the school or non-school levy determine the applicable valuation-for-assessment calculation.
Before relying on a date: Resolve the county and assessment year, read the current assessor notice, and determine whether standard or authorized alternate procedures apply. Verify the actual protest deadline and accepted channel, County Board petition instructions, decision date, and the selected Board of Assessment Appeals, court, or arbitration requirements before relaying a filing date.
State source: Colorado General Assembly, Colorado Revised Statutes, https://leg.colorado.gov/laws/colorado-revised-statutes. Reviewed 2026-10-05.
State source: Colorado General Assembly, HB25-1324 — Property Tax, https://leg.colorado.gov/bills/hb25-1324. Reviewed 2026-10-05.
State source: Colorado General Assembly, SB26-046 — Property Tax Administrative Procedures, signed act, https://leg.colorado.gov/laws/session-laws/SB26-046/10/download. Reviewed 2026-10-05.
State source: Colorado General Assembly, Legislative Council Staff, SB26-046 Final Fiscal Note — Effective Date, https://leg.colorado.gov/bill_files/117694/download. Reviewed 2026-10-05.
State source: Colorado Secretary of State, Amendments and Propositions on the 2026 Ballot, https://www.sos.state.co.us/pubs/elections/Initiatives/ballot/contacts/2026.html. Reviewed 2026-10-05.
State source: Boulder County Assessor, Real Property Valuation Appeals, https://bouldercounty.gov/property-and-land/assessor/appeals/. Reviewed 2026-10-05.
State source: Colorado General Assembly, HB24B-1001 — Property Tax, https://leg.colorado.gov/bills/hb24b-1001. Reviewed 2026-08-02.
State source: Colorado Department of Local Affairs, Board of Assessment Appeals Frequently Asked Questions, https://cdola.colorado.gov/board-of-assessment-appeals-homepage/board-of-assessment-appeals-faqs. Reviewed 2026-08-02.
Denver County: 2026 deadline guidance is 2026 assessor protest window closed June 8, 2026. Guide: https://fairpath.app/property-tax-appeal/colorado/denver-county
Montrose County: 2026 deadline guidance is 2026 real-property protest period closed June 8, 2026. Guide: https://fairpath.app/property-tax-appeal/colorado/montrose-county
Source: City and County of Denver, Denver Property Taxation and Assessment System, https://www.denvergov.org/property. Reviewed 2026-07-16.
Source: City and County of Denver Assessment Division, Assessor Frequently Asked Questions, https://denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Department-of-Finance/Our-Divisions/Assessors-Office/Assessment-FAQ. Reviewed 2026-07-16.
Source: Colorado Judicial Branch, Colorado Property Tax Appeal Self-Help, https://www.coloradojudicial.gov/self-help/property-tax-appeal. Reviewed 2026-07-16.
Source: Montrose County, Montrose County Assessor, https://www.montrosecounty.net/68/Assessor. Reviewed 2026-07-16.
Source: Montrose County Assessor, 2025 Reappraisal Single-Family Home Sales, https://www.montrosecounty.net/DocumentCenter/View/24968/2025-Single-Family-Home-Sales. Reviewed 2026-07-16.
Source: Montrose County Assessor, 2026 Real Property Notice of Valuation, https://www.montrosecounty.net/DocumentCenter/View/25793/2025-Tax-Bill-Insert. Reviewed 2026-07-16.
Source: Montrose County Assessor, Montrose County EagleWeb Property Record Search, https://eagleweb.montrosecounty.net/eagleassessor/web. Reviewed 2026-07-16.
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