Colorado property tax appeal · $49 flat · keep 100%
How to appeal your Colorado property taxes
Colorado assessors mail a Notice of Valuation (NOV) by May 1. Homeowners protest to the assessor in early June (the date is on the notice). If the assessor denies the protest, you can appeal to the County Board of Equalization, and beyond that to the Board of Assessment Appeals, binding arbitration, or district court. Values are set in odd-numbered reassessment years.
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See how the Colorado process worksThe second step after the assessor's June determination: appeal the assessor's Notice of Determination to the CBOE by Sep 15. Jeffco runs its own petition process through its Board of Equalization; hearings conclude by Nov 1.
Source: Jefferson County, CO — Appealing Real Property Valuation (CBOE due date) · verified September 12, 2026Colorado lets you petition to correct an erroneous valuation for the two prior tax years, even though the protest deadline for those years is long gone. The deadline is the first working day of the January following the two-year mark, which for tax year 2024 is Monday, January 4, 2027 (Golden Aluminum Co. v. Weld County BOCC, 867 P.2d 190). On OVERVALUATION grounds it is barred only if you both filed a protest AND the assessor mailed you a notice of determination for that year; a protest alone does not bar it, and other grounds such as a clerical error are not barred at all. WE CANNOT SUPPLY THE EVIDENCE FOR THIS ONE. Colorado decides value from comparable SALES inside a fixed 18-month base period, and an abatement for tax year 2024 has to argue that year's level of value, not today's. Our Colorado comparables are current assessment values from a later cycle, so they do not support this petition. Read the window as a real deadline you may want to meet, not as something our report evidences.
Source: Colorado Division of Property Taxation — Assessors' Reference Library, Vol. 2 Ch. 5 (Abatement/Refund Process) · verified August 26, 2026Denver's published CBOE pages were stale when we checked, so we will not print a date we could not confirm. Colorado's default CBOE window runs to Sep 15; confirm Denver's with the county before relying on it.
Official calendar: City & County of Denver — Board of EqualizationColorado appeal deadline
Filing deadlineNext deadline: around June 8, 2027
June 8 (the date is also printed on your Notice of Valuation).
County assessors mail Notices of Value by May 1. Real property protests must be postmarked or made in person no later than June 8 (§39-5-121(1)(a), C.R.S.); personal property runs a separate June 30 clock. The date is also printed on your notice, and a handful of counties run an alternate calendar, so use your NOV where the two disagree.
How a Colorado appeal actually works
Every statement below is cited to its primary source and shows the date we verified it. Where we could not confirm something from a primary source, we say so instead of guessing. Dataset last re-verified 2026-08-13.
Missed the main deadline? Colorado has 4 remedies most homeowners never hear about
County pages rarely surface these. Each one is a distinct legal route with its own clock.
Abatement or refund petition - the remedy for taxpayers who missed the protest window
VERIFIED VERBATIM FROM DPT: 'Taxpayers who do not exercise the statutory rights listed above may petition for a change in valuation through the abatement or refund procedure. Abatements may be granted in cases of overvaluation as allowed by Secs. 39-10-114(1)(a)(I)(A) and (D), C.R.S., but CANNOT BE GRANTED IF THE VALUATION WAS PROTESTED DURING THE ASSESSMENT YEAR IN QUESTION, or if the declaration was not filed according to Secs. 39-5-107 and 108, C.R.S. However, if the following conditions are met, the taxpayer retains the right to file an abatement petition, Sec. 39-10-114(1)(a)(I)(D), C.R.S.' WHAT THOSE CONDITIONS ARE, since leaving them unstated reads as an absolute bar and is not: per the Assessors' Reference Library Vol. 2 Ch. 5, 'In cases of overvaluation, abatement action is barred if a protest was filed AND the assessor mailed a notice of determination for the assessment year for which abatement is sought, Sec. 39-10-114(1)(a)(I)(D), C.R.S.' BOTH conditions are required, so a protest that never produced a mailed notice of determination does NOT bar the abatement, and the bar reaches OVERVALUATION grounds only. Read 2026-08-26. THE CRITICAL PRODUCT IMPLICATION IS THE MUTUAL EXCLUSIVITY: filing a protest during the assessment year FORECLOSES the abatement route for that year. As in Texas under Sec. 25.25(d), a naive 'always protest' funnel can destroy a more valuable alternative remedy. Sequence deliberately. REFUND INTEREST - verified verbatim: 'With two exceptions, interest accrues from the date the taxes are paid pursuant to Sec. 39-10-114(1)(b), C.R.S.' The two exceptions: refund interest is not included in a refund of prior years' taxes where the error was a taxpayer error in completing personal property schedules under article 5 of title 39; and for refunds involving taxpayer errors or omissions in statements under article 7 of title 39, interest accrues from the date a complete abatement petition is filed if the county pays within the Sec. 39-10-114(1)(a)(I)(B) timeframe.
Sec. 39-10-114(1)(a)(I)(A), (D), C.R.S.; Sec. 39-10-114(1)(b), C.R.S.; Secs. 39-5-107 and 39-5-108, C.R.S. · primary source · verified 2026-08-12
Binding arbitration in lieu of BAA or district court
VERIFIED VERBATIM: 'The taxpayer may choose to use the binding arbitration procedure instead of appealing to the BAA or to the district court. No appeals from the decision of the arbitrator are permitted under Secs. 39-8-108(4) and 108.5, C.R.S. Specific arbitration procedures may be found in the ARL Volume 2, Chapter 5, Taxpayer Administrative Remedies or may be obtained from the county commissioner's office in each county.' Note the finality: unlike the BAA route, which carries a 49-day petition to the court of appeals, arbitration is terminal. That is a genuine risk to disclose and a reason to default customers to the BAA.
When:
primary source · verified
Right to be informed of the assessor's valuation methods on written request
VERIFIED VERBATIM FROM DPT, in the personal property context: 'At the written request of any taxpayer, the assessor must make every attempt to inform the taxpayer of the methods used to value the personal property as required by Sec. 39-5-121.5, C.R.S.' This is a statutory information right that most taxpayers never exercise and that materially improves the quality of a subsequent protest. Whether an equivalent right exists for real property was not verified.
Sec. 39-5-121.5, C.R.S. · primary source · verified 2026-08-12
Court of appeals review after a BAA decision
VERIFIED VERBATIM: 'If the petitioner has appealed to the Board of Assessment Appeals and the decision is against the petitioner he may, not later than 49 days after the decision, petition the court of appeals for judicial review. If the petitioner has appealed to the district court and the decision is against the petitioner, the petitioner may seek review by the court of appeals upon filing for such review according to the Colorado appellate rules as controlled by Secs. 39-8-108(3) and 24-4-106(9), C.R.S.' The 49-day figure is unusual and specific; calendar it precisely.
When:
primary source · verified
What evidence wins in Colorado
COLORADO'S DEFINING EVIDENTIARY FEATURE IS THE STRICTLY BOUNDED DATA GATHERING PERIOD, AND IT IS THE MOST COMMON REASON A COLORADO APPEAL FAILS ON A TECHNICALITY. Colorado values residential real property by the market approach using sales drawn from a statutorily defined base period, and SALES OUTSIDE THAT WINDOW ARE NOT ADMISSIBLE. VERIFIED FROM THE COLORADO BOARD OF ASSESSMENT APPEALS: 'The base period for a given tax year consists of the 18 months immediately prior to July 1 of the year before the assessment date. For tax years 2025 and 2026, the comparable properties must have sold between JANUARY 1, 2023 AND JUNE 30, 2024.' A comparable sale that closed in, say, September 2024 is worthless in a 2025 or 2026 Colorado appeal no matter how similar the property. Any comps engine ported from another state will silently produce inadmissible evidence in Colorado unless the base-period filter is enforced at the data layer. THE BASE PERIOD IS FIXED FOR BOTH YEARS OF THE BIENNIUM - the same January 1, 2023 to June 30, 2024 window governs both tax year 2025 and tax year 2026, which is a direct consequence of the biennial reassessment cycle. Colorado is a DISCLOSURE state, so sales data is obtainable, and the market approach is the operative method for residential property. The taxpayer's entitlement to present evidence is secured by Sec. 39-8-106, C.R.S. ('must be allowed to present witnesses and other evidence'), and both the BAA and district court hear the matter DE NOVO on evidence submitted at that hearing, so a weak CBOE record is repairable at level three - a significant structural advantage over Nevada.
primary source · verified 2026-08-12
The appeal ladder, in Colorado's own terms
- 1
County Assessor - protest / objection to real property valuation
Deadline: REAL PROPERTY: the Notice of Valuation is mailed by the assessor on MAY 1 of each year, and an appeal may be filed beginning MAY 1 THROUGH JUNE 8, with any mailed appeal POSTMARKED NO LATER THAN JUNE 8. THE DATE CHANGED RECENTLY AND OLD SOURCES SAY JUNE 1 - DO NOT USE JUNE 1. Colorado HB25-1324, 'Clarify Property Tax Objection & Protest Deadlines,' as enacted, states in its official summary: 'The act also updates the deadline for an assessor to conclude all hearings for objections and protests concerning valuations of taxable real property from June 1 to June 8 to better reflect the intent of previously enacted law.' The real property protest deadline is codified at Sec. 39-5-121(1)(a), C.R.S., and Sec. 39-5-122, C.R.S. provides that the assessor sits to hear real property protests beginning on the first working day after Notices of Valuation are mailed. THIS IS A DIFFERENT TRACK FROM PERSONAL PROPERTY - do not conflate them. PERSONAL PROPERTY (separate and later): Notices of Valuation for personal property are mailed no later than JUNE 15; to receive a hearing before the assessor between June 15 and July 5 the owner or agent must file a protest; all MAILED personal property protests are timely if POSTMARKED BY JUNE 30, or the next business day if June 30 falls on a holiday or weekend, and all protests made IN PERSON are timely if made no later than June 30 or the next business day, as controlled by Sec. 39-5-121(1.5), C.R.S. The assessor must respond in writing to any personal property protest no later than JULY 10, with justification for the decision included, as required by Sec. 39-5-122, C.R.S. ALTERNATE PROCEDURE COUNTIES HAVE LATER DATES - SEE county_variation_notes. Under the alternate protest and appeal procedures, the deadline for assessors to respond to real property protests is extended from the last regular working day in June to AUGUST 15.
Clock starts: Mailing of the Notice of Valuation (real property: May 1; personal property: no later than June 15)
Sec. 39-5-121(1)(a), C.R.S. (real property); Sec. 39-5-121(1.5), C.R.S. (personal property); Sec. 39-5-122, C.R.S.; Sec. 39-5-122.7, C.R.S. (alternate procedures); HB25-1324 (2025) · primary source · verified 2026-08-12
Not confirmed from a primary source: No statewide prescribed protest form number was verified. Colorado's Division of Property Taxation maintains a Forms Index at dpt.colorado.gov/forms-index, but it was not retrievable in this pass due to CloudFront blocking. DPT guidance confirms a protest may be made in person or in writing and that the taxpayer 'may contact the assessor in person or in writing and request a review,' implying no rigid form requirement, but this was verified for PERSONAL property only. AGENCY REQUIREMENT VERIFIED: 'If a representative or agent is used by the owner, a letter of agency or other document that conveys agency authorization from the owner must be obtained.' Check the official page before relying on this.Fee: $0
No filing fee is referenced for an assessor-level protest under Sec. 39-5-122, C.R.S. · primary source · verified 2026-08-12
- 2
County Board of Equalization (CBOE)
Deadline: THIS IS THE FIELD MOST LIKELY TO CAUSE A LOST APPEAL IN COLORADO, BECAUSE THE DEADLINE DEPENDS ON WHETHER THE COUNTY USES STANDARD OR ALTERNATE PROCEDURES. STANDARD PROCEDURE (real property): appeal to the CBOE is due JULY 15. ALTERNATE PROCEDURE (real property): appeal to the CBOE is due SEPTEMBER 15, the board must conclude hearings by NOVEMBER 1, and must notify petitioners of its decision within five business days. Counties with population over 300,000 ('mandatory counties') are REQUIRED to use the alternate procedures in any general reassessment year for real property valued biennially; any other county ('elective county') MAY use them. HB25-1324, as enacted, 'clarifies that the later deadlines for alternate procedures apply to all mandatory counties and elective counties that use alternate procedures.' PERSONAL PROPERTY (separate track, verified verbatim from DPT): 'If a taxpayer is not satisfied with the assessor's valuation determination and the taxpayer files an appeal to the County Board of Equalization (CBOE), either in a letter postmarked or by appearing in person no later than JULY 20, the right to an appeal before the CBOE is guaranteed. If July 20 falls on a holiday or weekend and the letter is postmarked or the taxpayer appears in person the next business day, an appeal before the CBOE also is guaranteed.' For personal property the CBOE begins sitting on July 1 to hear appeals from assessor value determinations under Sec. 39-8-104, C.R.S., must conclude hearings and render value decisions ON OR BEFORE AUGUST 5, and must mail its determination within five business days of making its decision. HEARING RIGHTS, VERIFIED VERBATIM: 'The taxpayer must be notified of these hearings, must be given the opportunity to attend, and must be allowed to present witnesses and other evidence, Sec. 39-8-106, C.R.S. The assessor or a representative of the assessor shall be present at hearings on appeal as required by Sec. 39-8-107, C.R.S.'
Clock starts: The assessor's Notice of Determination denying the protest
Sec. 39-8-104, C.R.S.; Sec. 39-8-106, C.R.S.; Sec. 39-8-107, C.R.S.; Sec. 39-5-122.7, C.R.S. (alternate procedures); HB25-1324 (2025) · primary source · verified 2026-08-12
Form: Appeal to the County Board of Equalization (letter or county-issued petition; may be perfected by appearing in person)
primary source · verified 2026-08-12
Fee: $0
No filing fee is referenced for a CBOE appeal in DPT's description of the process · primary source · verified 2026-08-12
- 3
THREE PARALLEL OPTIONS from a CBOE decision: (a) Board of Assessment Appeals (BAA), (b) district court, or (c) binding arbitration
Deadline: THIRTY DAYS from the CBOE decision, for whichever of the three routes is chosen. Verified: 'If you wish to appeal a BOE decision, you must do so within 30 days of the decision.' THE THREE ROUTES ARE MUTUALLY EXCLUSIVE AND VERIFIED VERBATIM FROM DPT: (a) BOARD OF ASSESSMENT APPEALS - 'When taxpayers disagree with the decision of the CBOE, they may file an appeal with the Board of Assessment Appeals (BAA). The hearing is a de novo hearing meaning that it is a new hearing based upon evidence submitted at the hearing. The CBOE and the taxpayer both present cases for the record before the BAA, Sec. 39-8-108, C.R.S.' (b) DISTRICT COURT - 'The taxpayer may appeal the decision of the CBOE to the district court of the county wherein the property is located. The hearing before the district court is a trial de novo and each party must present its case for the record as required by Sec. 39-8-108, C.R.S.' (c) BINDING ARBITRATION - 'The taxpayer may choose to use the binding arbitration procedure instead of appealing to the BAA or to the district court. NO APPEALS FROM THE DECISION OF THE ARBITRATOR ARE PERMITTED under Secs. 39-8-108(4) and 108.5, C.R.S. Specific arbitration procedures may be found in the ARL Volume 2, Chapter 5, Taxpayer Administrative Remedies or may be obtained from the county commissioner's office in each county.' BOTH BAA AND DISTRICT COURT ARE DE NOVO - the CBOE record does not constrain the third-level hearing, which is materially more forgiving than Nevada and comparable to Utah. FURTHER APPEAL - verified verbatim: 'If the petitioner has appealed to the Board of Assessment Appeals and the decision is against the petitioner he may, NOT LATER THAN 49 DAYS AFTER THE DECISION, petition the court of appeals for judicial review. If the petitioner has appealed to the district court and the decision is against the petitioner, the petitioner may seek review by the court of appeals upon filing for such review according to the Colorado appellate rules as controlled by Secs. 39-8-108(3) and 24-4-106(9), C.R.S.'
Clock starts: The County Board of Equalization's decision
Sec. 39-8-108, C.R.S.; Sec. 39-8-108(3), (4), C.R.S.; Sec. 39-8-108.5, C.R.S.; Sec. 24-4-106(9), C.R.S. · primary source · verified 2026-08-12
Form: Petition for Appeal to the Board of Assessment Appeals official form
primary source · verified 2026-08-12
Fee: BOARD OF ASSESSMENT APPEALS: taxpayers WITHOUT AN ATTORNEY pay NO FEE for the first two petitions filed, and $33.75 for the third and subsequent petitions. ATTORNEYS AND AGENTS pay $101.25 for ALL petitions. DISTRICT COURT: civil filing fee set under Colorado law, not verified. ARBITRATION: arbitrator costs, not verified. (statutory)
BAA filing fees; specific statutory or rule citation not verified · primary source · verified 2026-08-12
When values are set
BIENNIAL. Real property is REVALUED EVERY ODD-NUMBERED YEAR. This is verified from the Colorado Division of Property Taxation. HB25-1324 corroborates the structure, referring to 'any general reassessment year for real property that is valued biennially.' The practical consequences are substantial and often misunderstood. First, the same valuation carries across both years of the biennium, and the same 18-month base period governs both years - the BAA confirms that for tax years 2025 and 2026 alike the comparables must have sold between January 1, 2023 and June 30, 2024. Second, the appeal right EXISTS IN BOTH YEARS - an intervening-year protest is available - but the odd-numbered reassessment year is when new values are set and when the appeal has the most leverage, and it is the year in which mandatory counties must use the alternate procedures. Third, because a win in an odd year carries into the even year, a single successful Colorado appeal produces TWO YEARS of savings, which is a materially better economic proposition per appeal than any annual-cycle state in this region. PERSONAL PROPERTY is on a separate annual track with Notices of Valuation mailed no later than June 15 each year; under section 20(8)(c) of article X of the Colorado Constitution, personal property NOVs must be mailed by the assessor to each owner of taxable personal property EVERY YEAR.
primary source · verified 2026-08-12
How counties differ
COLORADO HAS THE MOST CONSEQUENTIAL COUNTY VARIATION OF ANY STATE IN THIS REGION, AND GETTING IT WRONG COSTS THE APPEAL. Two parallel deadline regimes exist for real property. STANDARD PROCEDURES: assessor protest May 1 through June 8; assessor Notice of Determination by the last regular working day in June; CBOE appeal due July 15 (NOT VERIFIED - see gap note). ALTERNATE PROTEST AND APPEAL PROCEDURES under Sec. 39-5-122.7, C.R.S.: assessor protest May 1 through June 8; assessor response deadline extended to AUGUST 15; CBOE appeal due SEPTEMBER 15; CBOE must conclude hearings by NOVEMBER 1 and notify petitioners within five business days. WHO USES WHICH: a county with population over 300,000 is a MANDATORY county and is REQUIRED to use the alternate procedures in any general reassessment year for real property that is valued biennially. Any other county is an ELECTIVE county and MAY use the alternate procedures, which must be approved by the county's governing body. HB25-1324, as enacted, exists precisely because this was being applied inconsistently - its official summary states the act 'clarifies that the later deadlines for alternate procedures apply to all mandatory counties and elective counties that use alternate procedures.' PRACTICAL REQUIREMENT: the product must maintain, per county per year, (a) whether that county is operating under standard or alternate procedures, and (b) the resulting CBOE deadline. It cannot be inferred from population alone, because elective counties opt in by action of their governing body and may change year to year. Denver, El Paso, Arapahoe, Jefferson, Adams, Larimer, Douglas and Weld are the counties most likely to exceed the 300,000 threshold and thus to be mandatory alternate-procedure counties in a reassessment year, but EACH MUST BE CONFIRMED against the latest population determination rather than assumed. PERSONAL PROPERTY runs on a single statewide annual track regardless of procedure type: NOV by June 15, assessor hearing between June 15 and July 5, protest postmarked or made in person by June 30 with an express next-business-day roll, assessor written response by July 10, CBOE appeal by July 20 with an express next-business-day roll, CBOE concludes by August 5 and mails within five business days. Binding arbitration procedures are administered county by county and 'may be obtained from the county commissioner's office in each county.'
The Colorado appeal process, step by step
1. Notice of Valuation (by May 1)
Your county assessor mails a Notice of Valuation by May 1 showing your new actual value. Colorado reassesses in odd-numbered years (the last was 2025); in even years values usually carry forward, but you can still protest.
2. Protest to the assessor (early June)
File a written protest with the assessor by the deadline printed on your NOV, typically the first week of June. Include 3-5 comparable sales from the state's defined data-gathering period. No filing fee.
3. Assessor's determination (Notice of Determination)
The assessor reviews your protest and mails a Notice of Determination, usually by late June. If you disagree, you may appeal to the County Board of Equalization (CBOE).
4. County Board of Equalization hearing
The CBOE hears appeals, generally in July. Present your comparable-sales evidence to a referee or the board. Confirm your hearing date with the county.
5. Further appeal (optional)
If the CBOE denies your appeal, you generally have 30 days to escalate to the Board of Assessment Appeals (BAA), binding arbitration, or district court.
Colorado counties
County-specific filing notes for Colorado's largest markets. More counties added as we expand.
Denver County
Denver
Notice of Valuation mails by May 1; protest by the early-June date on your notice. No filing fee.
El Paso County
Colorado Springs
Colorado Springs metro. Protest to the assessor in early June using the date printed on your Notice of Valuation.
Arapahoe County
Littleton
South metro Denver. File your written protest by the early-June deadline on your NOV.
Jefferson County
Golden
West metro Denver. Protest to the assessor in early June; escalate to the CBOE if denied.
Douglas County
Castle Rock
Fast-growing county between Denver and Colorado Springs. Use the protest date printed on your Notice of Valuation.
Boulder County
Boulder
Protest to the assessor in early June. Boulder values run high, so comparable-sales evidence matters.
Colorado property tax appeal FAQ
When is the Colorado property tax protest deadline?
Early June, the exact date is printed on your Notice of Valuation, which assessors mail by May 1. Recent law has shifted the date for some counties, so rely on your notice rather than assuming June 1.
Is there a fee to protest property taxes in Colorado?
No. Protesting to the assessor and appealing to the County Board of Equalization are free.
Are you missing a Colorado exemption?
Exemptions cut your bill before any appeal even starts, and most homeowners never claim all the ones they qualify for. Answer four questions:
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