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Colorado works, and the next reassessment wave is 2027.
The law and the data both work here. No cap on individual assessments, a uniform statewide ratio, and sale prices are public by design, because the documentary fee exists to build that public record. Denver saw 24,747 appeals and Jefferson County about 28,300 in the last reassessment year.
So Colorado decides these on market value, which means the evidence is recent sales of genuinely comparable homes. What really matters is whether that whole set of sales sits below your assessed value. If they bracket your assessment instead of falling under it, boards usually side with the assessor, because nothing's been clearly disproved.
Now a few things lose almost everywhere. Comparing your assessment to a neighbor's assessment usually doesn't count where the argument's market value. One sale on its own can pretty easily be dismissed as an outlier. And the size of your increase, or the size of your bill, isn't really evidence about what your home's worth.
June, in reassessment years. 2026 is an off year, so the next real wave is 2027.
Miss it and you generally wait a year, so honestly the date matters more than the paperwork does.
And wherever you are, the single most useful thing you can actually do today is go find your assessment notice and read the date printed on it. That's what starts your clock, it's usually a much shorter window than people expect, and there's no getting it back once it's gone.
We've measured how sales compare with current values, town by town, in Denver, Jefferson, Arapahoe, Douglas, Adams, Larimer, Boulder and Weld counties. Denver, Arapahoe and Boulder have softened, while the others' houses are still selling above their values. Our free check for all eight'll run once the 2027 notices are out in May, and it's pretty much the same rules and dates in every Colorado county.
First, look up your own record. Your county assessor mails a Notice of Valuation in the spring, and their website's got your home's record. Colorado values every home as of a set date, which honestly surprises a lot of people, June 30 of the year before a reassessment year, so the 2025 and 2026 values are both based on the market as of June 30, 2024.
Next, know where to file. You'll protest to the county assessor first, by June 8. The assessor's got to send a Notice of Determination by the last working day of June. If you still don't agree, you can appeal to your County Board of Equalization by July 15.
Then bring the evidence that wins here. The evidence that really counts is sales of genuinely similar homes from the period before that June 30 valuation date. Today's prices don't, and that's the part most people miss.
Also, check your exemptions. The senior homestead exemption takes 50 percent off the first $200,000 of your home's value if you're 65 or older and have owned and lived in it for at least 10 years. You'll apply with your county assessor by July 15. The state only funds it when its budget allows, so it's worth checking whether it's being paid this year.
We only turn a state on once we've read its appeal rules and its actual board decisions, because that's how we make sure what we tell you is right and not generic. It takes a few days per state, and honestly it's the reason our answers are worth anything.
In the meantime our free check runs in parts of Illinois, Washington, Ohio, Georgia, Colorado, North Carolina and Oregon, and in every town in New Jersey. If you leave your email on the check page, we'll write to you the day Colorado goes live, and we won't email you before that.
We've screened all fifty states and DC on the same two questions. Does winning a lower market value actually lower your bill, or is there a cap sitting in between? And can you even put the evidence together from public records?
This comes from our own fifty-state screen, where we checked each state's cap, whether sale prices are public, whether there's an argument based on assessed values, and how many appeals actually get filed. Where we've quoted an appeal count, it's from the state or county that published it. If you spot an error, please write to hello@propertytaxbuddy.com and we'll correct it and say what changed.