State Guide

How to Appeal Your Property Taxes in Colorado (2026 Guide)

Published July 13, 2026

If you own a home in Colorado, your county assessor mails you a Notice of Valuation each spring showing the actual value — what the county believes your home would sell for — and that figure ultimately drives your tax bill. You get a short statutory window to challenge it, and in Colorado that window closes on June 8.

The Colorado deadline: June 8 to the assessor

Colorado's first-rung appeal — a protest to the county assessor — must be delivered or postmarked by June 8. That date is worth a second look: for years the statute read June 1, but HB25-1324 (2025) amended C.R.S. §39-5-122 to move the protest and hearing deadline to June 8, "to better reflect the intent of previously enacted law." If you're working from an older guide, you may see the wrong date — the current deadline is June 8.

The window opens when your assessor mails the Notice of Valuation, which generally goes out by May 1. Colorado reappraises residential property on a two-year cycle in odd-numbered years (2025, 2027, and so on), so that's when values move the most — but you can protest in any year you believe the actual value is too high. Miss June 8 and you generally forfeit the assessor-level protest for that year.

What you're actually appealing: the actual value

Here's the part that trips people up. Colorado does not tax your home at 100% of its value, and it does not use one flat statewide ratio you can argue about. Your assessed value = actual value × a residential assessment rate, and that rate is set by the legislature and adjusted almost every cycle. There are two rates — for 2026, 6.8% for local governments and 7.05% for schools (C.R.S. §§39-1-104(1), 39-1-104.2). The local-government rate also gets a subtraction first: 10% of your home's actual value, up to $700,000 (floor $1,000), then the 6.8% rate applies to what's left — schools use the full actual value with no subtraction. So a $600,000 home has $60,000 subtracted before the local-government math: ($600,000 − $60,000) × 6.8% = $36,720 for the local-government portion, while the schools portion is $600,000 × 7.05% = $42,300.

You can't win by arguing the rate — the legislature sets it. What you can contest is the actual value, the 100% market figure the assessor assigned. That's the number your comparable sales attack directly, and every dollar you knock off it flows straight through to a lower assessed value and a lower bill. So read your notice for the actual value, not the assessed value, and build your case against it.

Category	Colorado
What you appeal	The actual (market) value on your Notice of Valuation
Assessment rate	Set yearly by the legislature; 2026 = 6.8% local gov (after a 10%-of-first-$700k subtraction) / 7.05% schools (§39-1-104.2)
Assessor protest deadline	June 8 (§39-5-122, per HB25-1324)
Next rung	County Board of Equalization — petition by July 15 (§39-8-106)
After that	BAA, district court, or arbitration — 30 days from the CBOE decision (§39-8-108)
Assessment growth cap	None — Gallagher's rate formula was repealed in 2020 (Amendment B)
Board can raise you?	Yes at the top rung (BAA / court / arbitration, since HB21-1083)

Is there a cap on how much your value can rise?

No — Colorado has no cap on how much your individual home's actual value can grow year to year. The old Gallagher Amendment adjusted the statewide residential rate downward as values climbed, but voters repealed it in 2020 (Amendment B / SCR20-001), so that automatic relief is gone. A conditional rule can shave the statewide rate by 0.1% if statewide value growth tops 5%, but that's a rate tweak applied to everyone, not a per-home assessment cap. In practice, that means when your neighborhood's values spike, your actual value can spike with them — which is exactly when an evidence-based protest pays off.

What evidence wins in Colorado

County boards want recent comparable sales, not opinions. The strongest case is three to five arm's-length sales of genuinely similar homes — same neighborhood, similar size, age, and condition — that sold near your assessment date and support a lower actual value than the assessor assigned. Photos of condition problems, a recent purchase price below the assessed actual value, or a fee appraisal help too. Vague complaints that "taxes are too high" do not move a board; a tight comparable-sales grid does.

What happens after you file — and the backfire risk

If the assessor denies your protest, you petition the County Board of Equalization (CBOE) by July 15; the CBOE issues decisions by around August 5 (§39-8-106, §39-8-107). If that still doesn't go your way, you have 30 days from the mailing of the CBOE decision to choose one of three routes: the Board of Assessment Appeals (BAA), your county district court (a fresh, de novo hearing), or binding arbitration (final, no further appeal) — C.R.S. §39-8-108.

One warning specific to Colorado: it's a backfire state at the top rung. Under HB21-1083 (2021), the old rule barring an increase on the owner's own appeal was removed, so the BAA, a district court, or an arbitrator can raise your value if the evidence supports a higher number. The assessor-protest and CBOE stages are low-risk places to make your case; just go in with solid comparable sales before you escalate past the CBOE, because at that level the value can move in either direction.

Confirm every date and figure against your own Notice of Valuation and your county assessor's page — county calendars and the yearly assessment rate can shift — and file before June 8.

Property tax rules and deadlines vary by jurisdiction and can change — verify with your county before relying on this.