Colorado Property Assessment Appeals

Argue the value or record, not the size of the bill

If the assessor's value is too high, build your appeal around evidence of value. A protest that just says "taxes are too high" usually misses the mark. Instead, show why the actual value, the classification, or the property details are wrong.

A simple example

Suppose the county record says the home has a finished basement, but the basement is unfinished. Send the record card, clear photos, and any inspection or permit evidence. Ask the assessor to correct that fact and explain how it affected the value. That is stronger than comparing your tax bill with a neighbor's bill.

What evidence helps

Good evidence is specific and tied to the county's valuation date. Ask the assessor which sales period applies before relying on a recent listing or sale.

• the county property record with a wrong size, feature, use, or classification marked clearly
• the assessor's comparable sales and better comparable sales from the same valuation period
• dated photos, inspection findings, or repair bids that show the property's condition
• an appraisal that addresses the value date used for the assessment
• a short explanation of the value or record change you are asking the county to make

The deadline matters

Colorado gives you a short spring filing window after value notices go out. For the 2026 cycle, the standard real-property protest deadline was June 8. A law that takes effect August 12, 2026 changes that standard deadline to June 1 for later cycles. Counties using an alternate schedule can differ. Use the date printed on your notice and the county assessor's current instructions.

If the assessor says no, the appeal is not necessarily over

The assessor's notice of determination tells you whether the value changed and how to ask the County Board of Equalization to review the result. If that board denies the appeal, its decision should list the next choices. Those can include the Colorado Board of Assessment Appeals, district court, or binding arbitration.

Do not rely on an old calendar or assume every next step is due in 30 days. Colorado changed parts of the schedule in 2026, and counties using an alternate process can have different dates. Use the deadline printed on the decision, save every filing and attachment, and act as soon as the notice arrives.