Level 2 Fire Restrictions in effect for western areas of Boulder County. No fireworks, fires, open flame, or shooting (see map and flyer).

Many County services are being offered online. Additionally, a variety of resources are available for those impacted by COVID-19.

Property Tax Calculation

How Property Taxes Are Calculated

Actual Value, Assessment Rate, and Mill Levy

Property taxes are calculated using the actual property value, the assessment rate, and the mill levy using the formula: Actual Value x Assessment Rate = Assessed Value x Mill Levy = Taxes Due. More information is available in the Calculating Your Property Taxes flyer. For example:

property tax calculation

For a residential property with an Actual Value of $350,00, an Assessment Rate of 7.15%,
and a Mill Levy of 86, there will be $2,152 in taxes due.

property tax calculation

Additional details on the Assessment Rate and Mill Levy are below. Seniors and disabled veterans may qualify for certain property tax exemptions.

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

Assessment Rate

Currently, assessed property values are calculated by multiplying the actual value by 7.15% for residential properties, and by 29% for non-residential properties. These percentage numbers are determined by state law.

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 the county as $100,000,000.
  • The Board of County Commissioners 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)
  • The county tax rate is $13.98 in revenue needed for each $1,000 of assessed value

Contact Us

Due to COVID-19, all Assessors Office sites are closed for business until Sunday, May 31. Please call or email us with your questions during our normal business hours.

Assessor
Phone: 303-441-3530
Fax: 303-441-4996

Business Personal Property
Phone: 303-441-3316
Fax: 303-441-1783

Email

Schedule a meeting

Mailing Address
Main: PO Box 471
Boulder, CO 80306-0471

Locations
Boulder
1325 Pearl St., 2nd floor
Boulder, CO 80302
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Hours: 8 a.m.-4:30 p.m. M-F

Longmont
515 Coffman Street, Suite 114
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Lafayette
1376 Miners Dr., Unit 105
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