This post is based on the Adams County, CO tax appeal process. Other counties might have slightly different processes or deadlines, but the basics are the same. I have provided links to the 5 major counties in the Denver area at the bottom of the post.
Colorado state statutes require County Assessors to revalue all Real Property every two years, on the odd number year (2023). The value of your home is used for the basis to determine how much you will pay for your 2023 and 2024 property taxes. If you feel the value assigned to your property is too high, you have the right to appeal your property tax value between May 1 and June 8th, 2023.
Getting Our Heads Straight
Even years, odd years, reappraisal years, intervening years, sales data collection period, appraisal date, assessment date and appeal deadline date. If you know all of these along with your assessed value, your opinion of value (supported by comps), your account number and your access key, then you are set to appeal your property tax value and there is no need to continue reading this post. If your head is spinning, don’t worry – I’m going to make this easy for you. Just follow the steps below and your property tax appeal will be filed in no time.
Figuring Out The Timeline
Real property must be revalued every odd numbered year. The value is based on its value as of the appraisal date, which is June 30th of the year prior to the reappraisal year. The value of the subject property is based on an analysis of comparable sales to predict the price the property would have sold for on the appraisal date. That value stays with the property for 2 years (until the next reappraisal year). So, in other words – the value you would appeal today is the appraised value based on June 30th 2022. You get 2 chances to appeal this value (May 2023 and May 2024). Let’s look at a graphic to help us put these dates into perspective.
Tax appeal timeline

Three Easy(ish) Steps To Appeal Your Property Tax Value
Now that you know what you are appealing and when you can do it, let’s dive in and see if you should appeal, and if so – get it done.
Step 1 - Find Your Assessed Value
Appealing your taxes is easier in the odd years because the county sends you a Notice of Valuation (NOV). Your NOV should be mailed to you by May 1st, 2023. The NOV shows you the assessed value, your account number and your access key. This is what your NOV looks like:

If you don’t have your NOV, you can find your account number and total valuation on your tax bill or look them up online by using the resources on the bottom of the page. If you need your access key, you will need to call the Assessor’s office at 720-523-6038.
Step 2 - Find Comparable Properties (Comps)
You must determine the value of your property as of June 30, 2022. You cannot use appraisals completed or comps that sold after this date. Although the collection period goes from January 2021 through June 2022, they are trying to find the value as of June 2022, so I believe comps within 3 or 6 months of that date will probably carry more weight. There are several ways to find comparable sales:
County Website – Yeah, right – good luck with that one. I found it hard to navigate and find comps using the Adams County Assessor website, but you can try it here: http://www.adcogov.org/assessor.
The best way to get comps, is to ask me to get them for you. For one reason or another, I search comps almost every day using the MLS database. As a free service to you, I am happy to pull comps for you - just fill out and submit the form.
* You will get your comps within 5 days (usually sooner).

*By filling out this form, you agree to receive email.
Step 3 - Appeal Your Property Tax Value
If you feel your assessed value is too high, go to www.adcogov.org/assessor (or use the links below for a different county) and follow the prompts to appeal. You will need your account number and access key found in step 1. Attach your comps and provide a brief description of why your assessed property tax value should be lowered. Don’t forget – you lose your right to appeal your property tax value this year if don’t appeal by June 8, 2023.
County Websites For Property Tax Value Appeals
Adams County 720-523-6038
– Get value and account number using Quick Search search your street number and click on Valuation Summary.
– Get your access key: Call Jackie at 720-523-6743
– Appeal Here – I could not find forms for appealing, only an online option You can appeal by mail though.
Arapahoe County 303-795-4600
– Get value and account number – search your address then view property tax statement.
– Appeal Here – You can file online or if you don’t have your PIN and control number you can fill out, print and mail the downloadable form
Denver County 720-913-4162
– Appeal Here – Denver makes it very easy for you to appeal your property tax value. Simply go their website and search for your property address. They give you options to view comps, neighborhood, etc, as well as assessment protest button – you don’t need any pins, account #’s or secret keys. Very nice Denver!
Douglas County 303-660-7400
– Appeal Here – Douglas County has an easy to follow page on how to appeal your property tax value.
Jefferson County 303-271-8600
– Appeal Here – You can file online or if you don’t have your PIN and control number you can fill out, print and mail the downloadable form