How are property taxes calculated in Boulder?
The short answer
Boulder County multiplies your home's actual value by an assessment rate, then by the mill levy for your tax area. For the 2025 tax year, paid in 2026, the residential assessment rate is 7.05 percent for school district taxes and 6.25 percent for other local governments. The county's own example puts the tax on an $800,000 home at about $4,942, depending on your tax area.
Buyers moving from out of state ask this one often. The math is simple once you see the steps.
The three steps
First, the Boulder County Assessor sets your home's actual value. Second, that value is multiplied by the residential assessment rate to get the assessed value. For tax year 2025, payable in 2026, the rate is 7.05 percent for school districts and 6.25 percent for other local governments. Third, the assessed value is multiplied by the mill levy for your tax area. One mill is one tenth of one percent.
The county's example
Using an $800,000 home and example mill levies: 7.05 percent of $800,000 is $56,400, and at 30 school mills that is $1,692. 6.25 percent of $800,000 is $50,000, and at 65 local mills that is $3,250. The total is $4,942.
Your real mill levy depends on your exact tax area inside the city, the school district and any special districts. You can look up any address on the Boulder County Assessor's site before you make an offer.
Something to watch
Colorado has changed its assessment rates several times in the last few years. Check the current year's rates before you budget, and remember that values are reassessed every two years.
- Boulder County Assessor, Property Tax Calculation (tax year 2025, payable 2026)