Colorado Property Tax Appeals: June 8 Deadline & Process
Researched from official Colorado sources · Updated October 2026
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How Colorado Property Valuation Appeals Work
Colorado appeals run through three levels. You start with your county assessor, which is an informal protest. If you disagree with the assessor's answer you go to the County Board of Equalization (CBOE). After the CBOE you can go to the Board of Assessment Appeals (BAA), to district court, or to arbitration. Boulder County Assessor · Colorado Judicial Branch
The Deadline: June 8
Boulder and Jefferson counties both post the same window: you can file a valuation appeal with the assessor from May 1 through June 8. Mailed appeals must be postmarked by June 8. Jefferson County Assessor · Boulder County Assessor
The 2026 window has closed. Plan around May 1 to June 8, 2027 if the schedule holds, and read the dates on your own notice of valuation. The countdown above the county list tracks each county guide.
What Happens After You Protest
- Assessor's decision. The assessor mails a notice of determination by August 15 of the year of the appeal. Jefferson County
- County Board of Equalization. If you disagree with the determination, Boulder and Jefferson counties both list September 15 as the date to file with the CBOE. Jefferson County says the board must finish hearings by November 1 and notify petitioners within five business days. Your notice of determination carries the dates for your county, so use those. Boulder County · Jefferson County
- After the CBOE. You have 30 days from the date the CBOE decision was mailed to start one of three appeals: the Board of Assessment Appeals (a state board; contact it through the Colorado Department of Local Affairs for forms and any fees), a petition in the district court for your county, or arbitration. Colorado Judicial Branch
- Arbitration is final. The arbitrator's decision ends your right to further appeal. Colorado Judicial Branch
- District court filing fee. The Judicial Branch lists $235.00 for an administrative-hearing petition. The governing statutes are C.R.S. 39-8-106 through 39-8-108. Colorado Judicial Branch
What Evidence Works
County assessors ask for the same few things:
- Your own estimate of value.
- Comparable sales, with addresses, prices and sale dates.
- Corrections to the property record: square footage, bedroom and bathroom count, condition, improvements, with photos if you have them.
Boulder County lists an inaccurate estimated market value and errors in the property record as the two things you can appeal. Boulder County Assessor
Where Grove Hopper Fits
Grove Hopper is a research tool. We look at your property, flag whether it looks over-assessed and prepare your appeal documents. You review, sign and file them yourself with your county assessor. We are not attorneys, accountants or a tax firm. The free check is at the top of this page.
Pick your county below for its assessor and next date.
Colorado property tax FAQs
What is the deadline to appeal a Colorado property valuation?
Boulder and Jefferson counties post a protest window of May 1 through June 8, with mailed appeals postmarked by June 8. The 2026 window has closed, and the next one is expected May 1 to June 8, 2027. Check the dates on your own notice of valuation.
Who do I file a Colorado valuation protest with?
Your county assessor. It is the first, informal level. The assessor mails a notice of determination by August 15 of the year of the appeal.
What if I disagree with the assessor's decision?
Appeal to the County Board of Equalization. Boulder and Jefferson counties list September 15 as the filing date, and Jefferson County says hearings finish by November 1. Use the dates on your notice of determination.
How long do I have to appeal a Board of Equalization decision?
No later than 30 days after the date the CBOE decision was mailed to you. You can go to the Board of Assessment Appeals, file in district court, or choose arbitration, and an arbitrator's decision is final.
What evidence should I bring to a Colorado property appeal?
Comparable sales with addresses, prices and dates, your own estimate of value, and corrections to errors on the property record such as square footage or bedroom count, with photos if you have them.
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All 9 Colorado county guides
Grove Hopper is a research tool with reminders and document preparation. We prepare your appeal documents and you review, sign, and file them yourself. We never file or represent anyone, and we are not attorneys, accountants, or a tax firm. Dates and rules here come from the official pages linked above and can change; check your notice and your county's site before you file.
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