Why Did My Colorado Property Taxes Go Up So Much?

If your Colorado property tax bill jumped, you're not imagining it — and you're not alone. A handful of forces stacked up at once. Here's what drove the increase and which parts you can fight.

1. The reassessment reset your value

Colorado reassesses property every two years, and the 2025 reassessment captured several years of rapid price growth in one jump. Your tax is built on the assessor's actual value, so when that value resets upward, the bill follows. The value is produced by a mass-appraisal model — it's an estimate, and estimates can be too high.

2. Values are based on a past market window

By law, residential values come from sales during an 18-month data-gathering period ending June 30 of the year before reassessment. If that window caught the peak, your value may reflect a hotter market than the one you're living in now — a common and very appealable mismatch.

3. Mill levies and the end of Gallagher

The repeal of the Gallagher Amendment removed the mechanism that used to automatically lower the residential assessment rate as home values rose. Combined with local mill levies set by school districts, cities, and special districts, that means rising values now flow more directly into bills. We unpack this in Gallagher is gone.

What you can actually change

• The actual value — if comparable sales or your home's condition say it's too high, you can protest it down.
• Record errors — wrong square footage, bath count, or a finished basement that isn't finished inflate your value and are easy wins.
• Condition the model can't see — an old roof, original kitchen, foundation issues, or a busy-road lot.

See whether your increase is beatable

Not every increase is wrong — but many are. Check your address and we'll pull your county's actual record, show how your value moved, and tell you honestly whether you have a case. Start with the signs of overassessment if you want to self-check first.