The Colorado Notice of Valuation Explained

The Notice of Valuation (NOV) is the document that opens Colorado’s appeal season: real property NOVs are mailed by May 1 each year, and the protest period they start runs through June 8. It is also a notice that reads differently depending on where you are in the odd-year revaluation cycle — which is the part most often misread.

What is on it

• The property’s location and classification — the classification matters, because it selects the assessment rate your property will carry.
• The value-relevant characteristics — size, age, condition and similar facts the assessor used. Errors here are among the easiest protests to win.
• Actual value for the prior and current years — the two-year comparison that shows the change the revaluation (or the intervening adjustment) produced.
• The protest instructions and the window dates — with the Division’s caution, stated on its own pages: statutory dates shift when they fall on weekends or holidays, so the dates printed on your notice and your assessor’s published dates are the ones to rely on.

Revaluation year vs. carryover year

Real property is revalued every odd-numbered year. In an odd year, your NOV carries the fresh revaluation — typically the year’s big move. In an even year, the value carries over from the last revaluation unless something changed — construction, destruction, a change in ownership or use — in which case the notice reflects that adjustment. For the 2025 and 2026 tax years, the comparable-sales window for residential valuation is January 1, 2023 through June 30, 2024.

What this tells you: the sales window is the evidentiary frame of your protest. A crash in the market since mid-2024 is not, by itself, evidence about the value set from the 2023–2024 window — the protest has to argue the value within the frame, or the specific characteristics and conditions that distinguish your property from the window’s sales.

What it does not tell you: your tax bill. The NOV shows actual value only — the rate and the mill levies that turn it into a bill are set later in the year, and the rate is legislative.

Worked example (illustrative)

Illustrative reading with made-up numbers — not your property.

1. Inputs: a NOV mailed May 1, 2026 (a carryover year) showing prior actual value $505,000 and current actual value $512,000, with a $7,000 increase attributed to an added finished basement.
2. Step — read the change: a small increase in an even year usually means an adjustment, not a revaluation. The notice’s characteristics section is where the cause lives.
3. Step — check the trigger: if the basement was never finished, the characteristic is wrong — the cheapest protest to win, because the evidence is photographs and permits, not market opinions.
4. Step — the window: file or appear by June 8; after the protest, the assessor’s Notice of Determination arrives (see the protest page).

What this page does not cover

Business personal property declarations and their separate calendar, and the assessor’s internal valuation methods for non-residential classes, are outside this page. The Division’s Understanding Property Taxes page cited below is the authority for the NOV’s contents and timing.