How Property Taxes Are Calculated

Actual Value, Assessment Rate, and Mill Levy

Assessment Rate

The Assessment Rate below reflects rates for the tax year 2025 that will impact taxes paid in 2026. For more information on the 2025 assessment rates, please visit the Division of Property Taxation’s Assessment Rates web page.

2025 Assessment Rates and Value Adjustments

Type of Property	2025 Assessment Rate	2025 Value Adjustment
Residential	7.05% school districts 6.25% local government	$0
Lodging	27%	$0
Renewable Energy	27%	$0
Agricultural	27%	$0
Vacant Land	27%	$0
Commercial	27%	$0
Industrial	27%	$0
Oil & Gas production	87.5%	$0

Beginning in tax year 2025 (payable in 2026), there are two assessment rates; one for school districts and one for all other local government districts (fire districts, cities, etc.). For more information on the 2025 property tax calculation, please visit the Understanding Property Taxes in Colorado web page.
School Districts Calculation

Actual
Value
X
Schools
Assessment
Rate
=
Schools
Assessed
Value

and then

Schools
Assessed
Value
X
Schools
Mill
Levy
=
Schools
Taxes
Due

Other Government Districts Calculation

Actual
Value
X
Other
Assessment
Rate
=
Other
Assessed
Value

and then

Other
Assessed
Value
X
Other
Mill
Levy
=
Other
Taxes
Due

Property Tax Calculation Total

School
Taxes
Due
+
Other
Taxes
Due
=
Total
Taxes
Due

The example below is for a residential property with an Actual Value of $800,000 for tax year 2025, paid in 2026, with an Residential Assessment Rate of 7.05% for school districts, and 6.25% for local government. The school district’s Mill Levy is 30, and for all other local government districts that serve this property, the total Mill Levy is 65. The taxes would be calculated as follows:
School Districts Example

$800,000
X
7.05%
(or 0.0705)
=
$56,400

and then

$56,400
X
30
(or 30 Mills
or 0.03)
=
$1,692

Other Government Districts Example

$800,000
X
6.25%
(or 0.0625)
=
$50,000

and then

$50,000
X
65
(or 65 Mills
or 0.065)
=
$3,250

Property Tax Calculation Total

$1,692
+
$3,250
=
$4,942

Additional details on the Mill Levy are below. Seniors and disabled veterans may qualify for certain property tax exemptions that could impact their final tax amount.

Much more information on property taxes, including Property Tax Search, due dates, and paying taxes online, is available on the Boulder County Treasurer page.

Tax Rate or Mill Levy

The Tax Rate and Mill Levy are two different ways of expressing the same information. The Tax Rate is expressed as a percentage, while the Mill Levy is expressed in mills (1 mill = $1 of property tax for every $1,000 of assessed value)

Generally, properties are affected by several taxing entities. Each taxing entity determines what revenues will be required to operate during the coming fiscal year. The required revenues are then divided by the total assessed value to determine the tax rate/mill levy for each entity. To determine the total tax rate for a property, add the tax rates for each entity that impacts a property.

Mill Levy Example:

The assessor determines the total assessed value for properties within a school district’s boundaries as $100,000,000.
The school board of that school district determines the budgeted property tax revenues needed are $1,398,000.
$1,398,000 (tax revenue) divided by $100,000,000 (assessed value) = 1.3980% Tax Rate, or 13.98 Mills (Mill Levy), for that district’s portion of the total Mill Levy.
The school district’s tax rate is $13.98 in revenue needed for each $1,000 of assessed value.