A major source of funding for services from the City’s General Fund, including police services, fire services and library services, is property tax. The City levies a property tax of 13.42 mills. A mill is equal to $1 dollar of property tax for every $1,000 of assessed value of a property. Property assessment is a function of the county assessor. For more information on property assessment and billing or payment of property taxes visit the Boulder County Assessor's Office at BoulderCounty.org/departments/assessor.

Under state statute, the City cannot raise its mill levy rate without a vote of the electors in a November election. The 13.42 rate of mill levy has been in place since 1991. The City is projected to receive up to $16,210,313 of property tax revenue for its General Fund in 2017 after deduction of a 1.5% collection fee from the county treasurer.