Colorado underwent a major property tax reassessment cycle in 2023 that shocked many homeowners with increases of 30–50% or more in the Denver metro and Front Range communities. The state legislature has since passed temporary relief measures, but the underlying assessed values remain high — and appeals remain one of the most effective tools available.
How Colorado Property Taxes Work
Colorado reassesses all properties every two years on odd-numbered years (e.g., 2023, 2025). Residential properties are assessed at 6.765% of their actual value (as of 2023 reforms — this rate has been subject to legislative adjustment). The assessor uses sales from the prior 18-month period ending June 30 of the year preceding reassessment to establish values.
The key concept: if comparable homes in your neighborhood sold below your assessed value during that 18-month window, you have grounds for appeal.
The Deadline: June 8
Colorado’s appeal deadline is June 8 of the assessment year (in odd-numbered reassessment years). Assessment notices go out in May. For non-reassessment years, you can still appeal if you believe there’s been a change in your property’s condition or if an error exists.
Step-by-Step: The Colorado Appeal Process
Step 1: Review Your Notice of Valuation
Your Notice of Valuation arrives in May during reassessment years. It shows your Actual Value (market value) and the Assessed Value (used for tax calculation). Research sales of comparable properties that closed between January 1, 2022 and June 30, 2022 (for 2023 reassessment) — these are the sales the assessor used.
Step 2: File an Abatement Petition with Your County Assessor
File a written protest with your county assessor by June 8. Most counties accept online, mail, or in-person filings. Your protest should state your opinion of value and include comparable sales supporting it. The assessor must respond by August 15 with either an adjusted value or a denial.
Step 3: Board of Assessment Appeals (BAA)
If the assessor denies your protest or doesn’t provide a satisfactory reduction, appeal to the Colorado Board of Assessment Appeals (BAA) within 30 days of the assessor’s decision. BAA hearings are formal but accessible — you can represent yourself, and the process is conducted by administrative law judges. Decisions typically arrive within 60–90 days.
Step 4: District Court
For significant disputes, you can bypass the BAA and file directly in District Court, or appeal a BAA decision to District Court within 45 days. This route requires an attorney for most property owners.
Denver Metro — Special Considerations
Denver, Jefferson, Arapahoe, Adams, and Douglas counties have seen the most dramatic reassessment increases. Jefferson County assessor’s office received record numbers of protests in 2023. If you own property in any of these counties and haven’t appealed your 2023 or 2025 assessment, it’s worth reviewing your comparable sales.
More State Guides
See the Full Appeal Playbook
Our complete guide covers evidence, hearings, and how to escalate if denied.
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