How to Appeal Your Denver Property Tax Assessment in 2026
A step-by-step walkthrough of the CBOE process with real deadlines, the Assessor's own tools, and the evidence strategies that work.
A step-by-step walkthrough of the CBOE process with real deadlines, the Assessor’s own tools, and the evidence strategies that work.
If you own a home in Denver and your 2026 property tax bill gave you pause, you’re not alone — and you’re not necessarily stuck with that number. Colorado law gives every property owner the right to challenge their assessed value. The Denver process is more accessible than most homeowners assume. You don’t need a lawyer. You don’t need to pay anyone upfront. You do need to move fast and build your case with the right data.
This guide explains exactly how to do that.
Why 2026 Bills Are Drawing a Second Look
Colorado reassesses residential properties on a two-year cycle. The assessments behind your 2026 tax bills were completed in 2025, using sales data from the prior two years. For Denver homeowners, that cycle landed during a stretch when the regional market ran up hard and then softened. Both things can be true: your home’s value did increase, and your assessed value may still be higher than what the market actually supports.
The Denver Assessor’s Office will release official median assessed-value change figures with the 2025 reassessment notices mailed in May 2026. [Editor’s note: Verify the specific median change percentage with the Denver Assessor’s Office before publication — figures are released with the May notice mailing.] When those numbers come out, watch for the spread between assessed value and actual neighborhood sale prices. That gap is where appeals are won.
Here’s why even a modest overassessment is worth disputing, and it’s a question we return to often in our home & property coverage. Denver’s residential mill levy is applied to 6.95% of your assessed value. A $65,000 reduction in assessed value can translate to $500–$700 a year in tax savings — and that number doubles over a two-year cycle before the next reassessment. Whether a challenge is worth your time depends on how large the discrepancy is and how clearly you can document it.
The Hard Deadline
The filing deadline for a formal appeal to the Denver County Board of Equalization (CBOE) is June 1, 2026. Miss it, and you forfeit your right to a formal hearing until the next reassessment cycle — two full years away. No exceptions.
The catch that trips people up every cycle: the clock doesn’t start January 1. The Assessor mails notices in May, which means you may receive yours with only three or four weeks left to file. That’s not a typo. Colorado statute sets the deadline at June 1 regardless of when the notice lands in your mailbox, so a notice that arrives May 10 gives you roughly three weeks to research, build a case, and file. [Editor’s note: Confirm the exact June 1 deadline directly with the Denver Assessor’s Office before publication — statutory dates can shift if June 1 falls on a weekend or holiday.]
Don’t wait for the bill. If you already suspect your assessed value runs high based on what homes in your neighborhood have been selling for, start pulling comparable sales now. You’ll have your case half-built before the notice arrives.
Denver Assessor’s Office:
- Address: 201 W. Colfax Ave., Dept. 406, Denver, CO 80202
- Phone: 720-913-4162
- Portal: assessor.denvergov.org
Staff can answer procedural questions but won’t coach you on building your argument. Don’t expect strategic advice over the phone.
Two Tracks — and Which One to Use First
Most coverage of Colorado property tax appeals treats the process as a single path. It isn’t, and missing the distinction costs homeowners time and leverage.
The informal protest runs roughly May 1 through June 1 — the same window as the formal appeal. You contact the Assessor’s Office directly, through the online portal, by phone, or in writing, and present your evidence. An analyst reviews it and may reduce the value without a hearing. Many homeowners who show up with clear comparable sales data get a partial reduction here and never need to go further. There’s no downside to trying it first.
The CBOE appeal is the formal route. You file a written appeal with the Denver County Board of Equalization — a body separate from the Assessor’s Office — which schedules a hearing with a hearing officer. The CBOE issues a written decision by the statutory deadline of August 5. This matters because it creates an official record and preserves your right to escalate. If the CBOE rules against you, you can appeal to the Colorado Board of Assessment Appeals (BAA) or, ultimately, to district court. Skip the CBOE and go only the informal route, and that escalation path closes — a costly mistake if the overvaluation is large.
The move that makes sense for most homeowners: file the informal protest as soon as your notice arrives, and file the CBOE appeal at the same time. You can withdraw the CBOE filing if the Assessor’s analyst resolves it. You can’t recover the CBOE deadline if you let it pass waiting to see how the informal protest goes.
Pull Your Own Record First
Before writing a word of your appeal, go to assessor.denvergov.org and look up your property record. Free. Takes fifteen minutes. Almost no competing coverage tells Denver homeowners this is something they can actually do.
The portal shows your assessed value and classification — confirming your property is listed as residential — plus square footage, bedroom count, lot size, and other physical characteristics. Check them against reality. Errors in the property record are among the easiest wins in an appeal. A garage counted twice, a basement incorrectly listed as finished living space — those require nothing more than documentation to fix. The Assessor’s office corrects factual errors without much friction when you can show them.
The portal also shows the sales data the analyst relied on when setting your value. Pull that list and look at the addresses on a map. Ask yourself whether those properties are genuinely comparable to yours — same neighborhood, similar lot size, same era of construction. A 1950s ranch on a quiet residential block being compared to a 2010 infill townhome is not a fair comp, and that kind of mismatch is what you’re looking for.
You can also see how your assessed value has changed across prior cycles. If the jump between 2024 and 2026 is substantially larger than what comparable properties on your block experienced, that belongs in your appeal. Print or screenshot everything before you file.
Building Your Comparable Sales Case
Colorado’s appraisal methodology for the 2026 assessment cycle uses a statutory valuation date of June 30, 2024, drawing on sales from July 1, 2022, through June 30, 2024. That two-year window is the only universe of sales that counts for formal CBOE purposes. Your neighbor’s house that sold in September 2024 is outside the window — frustrating, but that’s the statute. [Editor’s note: Confirm the comps window dates with the Colorado Division of Property Taxation before publication.]
The Assessor’s portal is the most authoritative source and uses the same data set the analysts work from. Search by address or parcel number, then look at the sales history tab for nearby properties. DMAR monthly market reports (Denver Metro Association of Realtors, dmar.org) include neighborhood-level median prices and sales volume by month, useful for establishing market trend context — showing, for instance, that values in your submarket peaked in mid-2022 and were softening by early 2024. Colorado Division of Property Taxation records provide statewide assessment and sales ratio data, more useful for understanding how Denver County’s overall assessment accuracy compares to state standards than for building individual comps.
Zillow and Redfin are fine for background research and hold up reasonably well in an informal protest. At a formal CBOE hearing, documented MLS records or county deed records carry more weight. If a real estate agent in your network will pull a comparative market analysis from MLS data, that’s more persuasive than a Zestimate printout. Worth asking.
A few neighborhoods worth flagging. Green Valley Ranch, where lot sizes and home ages vary widely within a few blocks, tends to generate assessment anomalies. Globeville and Elyria-Swansea present genuine valuation complexity because of proximity to industrial parcels and active development. Cherry Creek, Capitol Hill, Washington Park, and Hilltop saw some of the steepest assessed-value climbs and the most CBOE filings in recent cycles.
When you identify your comps, aim for three to five properties that sold within the valid window, are within a half-mile of your home, share similar square footage, and have comparable lot size and condition. If the Assessor’s own comps don’t meet that standard, say so explicitly in your filing. That’s an argument, not just a complaint.
DIY or Hire Someone
The Assessor’s portal is free. The CBOE filing has no fee. No attorney is required at any stage through the CBOE. The informal protest can be submitted online in under an hour with comps in hand.
Professional consultants typically work on contingency — you pay nothing unless they win a reduction, then they take 25–40% of first-year tax savings. Here’s what that looks like concretely. A $575,000 assessed value translates to a taxable value of $39,962 (6.95% of $575,000). A successful appeal that reduces assessed value to $510,000 drops taxable value to $35,445. At current Denver mill levy rates, that’s roughly $500–$700 per year in savings. [Editor’s note: Verify using Denver’s actual 2026 residential mill levy once published by Denver Treasury.] A consultant taking 35% of first-year savings at $600 collects about $210.
For most homeowners with a straightforward single-family residence, that math points clearly toward doing it yourself. Spend an afternoon pulling comps and writing a short argument, keep the full amount. Professional help makes more sense on properties assessed above $800,000, on commercial or mixed-use parcels, on rental properties where income-approach valuation applies, or when the homeowner genuinely can’t do the research carefully. [Editor’s note: Insert names of two or three verified active Denver-area property tax appeal consultants here following direct outreach before publication. Do not name firms without confirmation.]
After You File
After an informal protest submitted online or by phone, expect a response from the Assessor’s Office within two to four weeks — longer during high-volume periods around the June deadline. The response comes by mail. Either your assessed value is adjusted or it isn’t. There’s no hearing; your written evidence does all the talking.
For the CBOE appeal, the board schedules a hearing and mails you notice of the date and time. Denver typically conducts these as informal evidentiary sessions with a hearing officer — not a courtroom proceeding. You present your evidence, the Assessor’s representative defends the valuation, the hearing officer asks questions. Organized, legible documentation matters. Vague arguments about feeling overcharged do not.
The CBOE must issue its decision by August 5, 2026. It arrives by mail and states the board’s determination of value.
If the CBOE denies your appeal, you can file with the Colorado Board of Assessment Appeals, an independent state agency. BAA hearings are more formal and typically take several months to schedule. If the BAA rules against you, the next step is district court, at which point getting a lawyer is genuinely advisable. Most cases with real merit resolve at the CBOE level. The BAA path is worth pursuing when the stakes justify it — a high-value residential property with a significant discrepancy, or when the CBOE hearing officer clearly declined to weigh relevant evidence.
Key Contacts, Deadlines, and Links
Denver Assessor’s Office
- Address: 201 W. Colfax Ave., Dept. 406, Denver, CO 80202
- Phone: 720-913-4162
- Online portal: assessor.denvergov.org
Denver County Board of Equalization (CBOE)
- Contact through the Assessor’s Office; CBOE filing information at assessor.denvergov.org
- Decision deadline: August 5, 2026
Colorado Board of Assessment Appeals (BAA)
- Independent state agency; contact information to be verified before publication
Key Dates
| Date | Action |
|---|---|
| May 2026 | Assessor mails 2025 reassessment notices |
| May 1 – June 1 | Informal protest window |
| June 1, 2026 | CBOE appeal filing deadline |
| August 5, 2026 | Statutory CBOE decision deadline |
| February 28, 2026 | First-half property tax payment due |
| June 15, 2026 | Second-half property tax payment due |
[Editor’s note: Confirm February 28 and June 15 payment dates with Denver Treasury before publication.]
Valid comparable sales window for 2026 assessment: July 1, 2022 – June 30, 2024 Statutory appraisal date: June 30, 2024
The CBOE isn’t a rubber stamp, but it’s also not a courtroom. Hearing officers know the market data and can tell when a comp is a stretch. What works is specific: here is what the Assessor said my house is worth, here is what comparable houses on comparable blocks actually sold for in the valid window, here is the gap. That’s the whole argument. The homeowners who get reductions built it clearly. The ones who showed up to complain generally didn’t. The June 1 deadline is the only thing that can’t be recovered. Everything else is paperwork.
