Colorado Property Tax Appeals Follow a Multi-Step Process in 2026
Colorado property owners who believe their property’s assessed value is inaccurate have a formal process for challenging the valuation. For the 2026 tax year, the initial protest period for most real property ran from May 1 through June 8, 2026, rather than October 15.
Colorado’s property valuation system operates on a two-year cycle. For the 2025 and 2026 tax years, real-property valuations were generally based on market conditions as of June 30, 2024.
Why the Appeal Process Matters
Property owners who believe an assessor’s valuation does not accurately reflect the property’s taxable value can submit evidence to support a different valuation.
The process is specifically a challenge to the property valuation or classification, rather than an appeal of the amount of the tax bill itself.
Who Can Challenge a Property Valuation?
The process can apply to owners of:
- Residential properties
- Commercial properties
- Other real property subject to assessment
- Business personal property, which follows a separate appeal schedule
For 2026, several county assessor offices identified June 8 as the deadline for real-property protests, while business personal-property protests generally had a June 30 deadline.
Evidence Can Strengthen an Appeal
Property owners challenging a valuation may provide documentation showing why they believe the assessor’s figure is inaccurate.
Potential supporting information can include:
- Comparable property sales
- Independent appraisal information
- Photographs showing property-condition issues
- Documentation of incorrect property characteristics
- Evidence of errors in the assessor’s property record
However, owners should pay close attention to the applicable valuation period. For the 2025–2026 valuation cycle, county assessors generally cannot use sales occurring after June 30, 2024 when determining the relevant value.
What Happens After the Assessor’s Decision?
If a property owner disagrees with the assessor’s determination, there may be another opportunity to appeal to the County Board of Equalization (CBOE).
For example, several Colorado counties list July 15, 2026 as the deadline for appealing a real-property valuation determination to the CBOE. County procedures should be checked carefully because filing requirements and dates can vary.
If a taxpayer remains dissatisfied after the county-level appeal, Colorado provides additional avenues, including the Board of Assessment Appeals, district court or, where available, binding arbitration.
What Property Owners Should Do
Anyone who believes a property valuation is incorrect should first contact the county assessor’s office where the property is located and review the property’s valuation records.
Because the initial 2026 real-property protest deadline has already passed in most counties, owners who missed that deadline should contact their assessor to determine whether another statutory remedy or appeal option is available for their particular circumstances.
Practical Consideration
Colorado’s property-tax appeal process involves specific deadlines and multiple stages. Property owners should not rely on a statewide date such as October 15 without checking the rules for their county and the type of property involved.
For future valuation cycles, keeping records of comparable sales, property improvements and condition issues can make it easier to review an assessment and prepare an appeal when the applicable protest period opens.