Colorado Property Tax Appeal Deadlines: Every Date You Can't Miss
The Colorado property tax appeal calendar — Notice of Valuation, the assessor protest deadline, Notice of Determination, County Board of Equalization, and the later appeal steps — with what to do at each stage.
Colorado property tax appeals run on a strict statutory calendar, and missing a date usually means waiting until the next cycle. Here's the sequence, why each deadline exists, and how to stay ahead of it.
The appeal calendar at a glance
| Stage | Typical timing | What happens |
|---|---|---|
| Notice of Valuation (NOV) mailed | By May 1 | County states your new actual value |
| Assessor protest deadline | On or about June 8 | You file your protest with the assessor |
| Notice of Determination (NOD) | By late June | Assessor accepts or denies your protest |
| County Board of Equalization (CBOE) | July (appeal filed shortly after NOD) | Appeal a denial; short hearing |
| Arbitration / BAA / District Court | Late summer onward | Further appeal of a CBOE decision |
Why the June deadline is the one that matters
The assessor protest deadline (around June 8 for real property) is the gate to the entire process. File on time and you can escalate all the way up the ladder; miss it and, in most cases, your value is locked for the rest of the two-year cycle. Because the window is short, the work — pulling the county record, building a comp set, writing the protest — has to be ready *before* it opens. See the full step-by-step appeal process.
Reassessment years vs. off years
Colorado reassesses in odd-numbered years (2025, 2027…), and that's when most homeowners protest because values reset. In even years you can still protest in limited situations — a record error, a change to the property, or other specific grounds. The value from a reassessment year carries into the following year, so a win compounds. More on the mechanics in why your taxes went up.
Don't watch the calendar alone
The simplest way to never miss a deadline is to prepare early and let someone track the county's exact dates for you. Start your free analysis now — we'll have your evidence ready and file the moment your county's window opens. Official dates and statutes are published by the Colorado Division of Property Taxation.
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