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Colorado · How-To Guide

How do I appeal my property tax assessment?

County Assessor (informal protest) / County Board of Equalization - CBOE (formal appeal) / Board of Assessment Appeals - BAA or District Court or Arbitration (further appeal)
Step by Step

How to do it

  1. Review your Notice of Valuation mailed by your County Assessor on or around May 1 each year (reassessment years: odd years are reassessment years; even years typically maintain prior value)
  2. FILE A PROTEST with the County Assessor between May 2 and June 8 (real property) - this is a hard statewide deadline; no extensions
  3. - Online: most Colorado counties now offer online protest filing through their county assessor's website
  4. - By mail: mail written protest form to County Assessor; must be postmarked by June 8
  5. - In person: visit County Assessor's office during protest period
  6. Gather supporting evidence: comparable sales from the assessor's look-back period, recent appraisal, photos of property condition, factual errors on property record (square footage, bedroom/bathroom count, etc.)
  7. Receive Notice of Determination from County Assessor (by June 15 in reassessment years)
  8. If unsatisfied with assessor's determination: file written appeal with the County Board of Equalization (CBOE) on or before July 15
  9. CBOE issues decision by August 5
  10. If still unsatisfied: within 30 days of CBOE decision, choose ONE next step:
  11. - Appeal to the Colorado Board of Assessment Appeals (BAA) at dola.colorado.gov/baa
  12. - Appeal to District Court
  13. - Binding Arbitration
Details

What you need to know

Required Docs
  • Written protest or completed protest form (county-specific; most counties have online forms)
  • Supporting evidence: comparable sales from the assessor's look-back period, recent appraisal, photos, factual documentation
  • Property parcel/schedule number and Notice of Valuation
Fee
No fee for Assessor protest or CBOE appeal; BAA filing fees apply; District Court filing fees apply KEY DEADLINES: - Protest to County Assessor: May 2 - June 8 (real property); June 16 - June 30 (business personal property) - Appeal to CBOE: July 15 (if unsatisfied with assessor's determination) - CBOE decision issued: August 5 - Further appeal (BAA/Court/Arbitration): within 30 days of CBOE decision ONLINE OPTION: Most counties offer online protest filing - check your county assessor's website WHERE TO GO: County Assessor (protest); County Clerk (CBOE filing); Colorado BAA - dola.colorado.gov/baa (further appeal)
Online Option
Most counties offer online protest filing - check your county assessor's website
Where to Go
County Assessor (protest); County Clerk (CBOE filing); Colorado BAA - dola.colorado.gov/baa (further appeal)
County-specific variations apply

Online protest filing availability varies by county - El Paso, Jefferson, Arapahoe, and Denver Counties have robust online systems. Some rural counties require written or in-person protest. Comparable sales evidence should be from the assessor's look-back period (June 30, 2024 for 2025 tax year), not current market data. Contact your specific county assessor for current year dates and forms.

Colorado Notes

Important state-specific details

  • Colorado uses a BIENNIAL reassessment cycle - reassessments occur in odd years; even years (2026) maintain the same value as the prior year for most properties. A successful appeal in a reassessment year benefits you for two tax years.
  • Comparable sales evidence must be from the assessor's LOOK-BACK PERIOD (June 30, 2024 for the 2025 tax year) - not current market conditions.
  • A successful appeal can theoretically result in a HIGHER value if you are under-assessed - verify comparables before filing.
  • Residential assessment rate for 2025-2026: 6.7% of actual value for local governments; 7.05% for school districts (split-rate system).
  • Senior/Veteran exemptions: apply separately at County Assessor - not part of the appeal process.
  • Colorado enacted significant property tax relief legislation following the 2020 repeal of the Gallagher Amendment - assessment rates have been adjusted; confirm current rate with your county.
Official Source

State office contact

State Office
Colorado Division of Property Taxation - colorado.gov/pacific/dpt | (303) 864-7777; Colorado Board of Assessment Appeals - dola.colorado.gov/baa | (303) 864-7710