Property taxes are always a hot topic, and 2026 brings important updates that homeowners, buyers, and investors should understand. While there’s no dramatic overhaul, a combination of reassessment timing, certified assessment rates, and state law changes may cause noticeable differences in tax bills.
Here’s a breakdown of what’s changing — and what it means for Boulder property owners.
How Property Taxes Are Set in Boulder
Property taxes in Boulder County are based on two main components:
- Your property’s assessed value, determined by the county assessor
- Mill levies, which are set by Boulder County, the City of Boulder, school districts, and other local taxing entities
Your total tax bill is calculated by applying mill levies to your assessed value. Even if mill levies remain stable, taxes can still increase when property values rise.
Reassessment
Boulder County reassesses property values every two years. The most recent reassessment took place in 2025, and those updated values are used to calculate property taxes payable in 2026.
For many homeowners, values remain higher than they were several years ago. As a result, even small mill levy changes can have a noticeable impact on tax bills.
Certified Residential Assessment Rates for Tax Year 2025
For tax year 2025 (payable in 2026), Colorado is using split residential assessment rates because statewide property value growth remained under 5%.
That means residential properties are assessed at different rates depending on which portion of the tax bill is being calculated:
- 6.25%: applies to the local government portion (city, county, special districts)
- 7.05%: applies to the school district portion
These rates are set at the state level and apply uniformly across Colorado.
State Law Changes: What’s Actually Different
Recent state legislation introduced two important concepts that affect how taxes are calculated:
1. A Value Exclusion Is Applied First
Before assessment rates are applied, a portion of a home’s value is excluded from taxation under the local government portion of the bill. This reduces the taxable value used for that portion only.
2. Split Rates Are Applied Separately
After the exclusion:
- The 6.25% rate is applied to the remaining value for local government taxes
- The 7.05% rate is applied separately for school district taxes, which do not receive the same exclusion
Because of this structure, homeowners still receive one tax bill, but it’s calculated using multiple formulas behind the scenes.
It’s important to note: Even with exclusions and reduced rates, your final tax bill still depends heavily on your property’s valuation and local mill levies. If your assessed value increased significantly, that increase can outweigh the relief measures.
Important Dates Homeowners Should Know
If you own property in Boulder, keep these dates in mind:
- Valuation notices mailed: First week of May 2025
- Appeal deadline: June 9, 2025
- Tax bills issued: January 2026
- Pay in full by April 30, 2026
- Or pay in two installments:
- First payment: March 2, 2026
- Second payment: June 15, 2026
What This Means for Boulder Homeowners
For most homeowners, 2026 property taxes will reflect a combination of:
- Updated 2025 reassessed values
- State-mandated value exclusions
- Split residential assessment rates
- Locally approved mill levies
Some property owners may see minimal changes, while others (particularly those with large valuation increases) may notice higher tax bills despite statewide relief efforts.
Understanding how these pieces fit together can help you plan ahead and avoid surprises when tax bills arrive.