Assessment & Valuation

Real Property Assessment & Valuation

State Mandate for the Valuation of Properties

State statute requires that each property in the county be re-valued by the County Assessor in odd numbered years.

The Assessor’s Role

The Boulder County Assessor identifies and values all property within Boulder County in accordance with state law. The goal is to equalize property values so taxes are distributed fairly and equitably between property owners.

When Property Is Valued

The Assessor’s Office reappraises the value of real property (land and buildings) every odd-numbered year. The value is stated as of the appraisal date, which is June 30 of the year prior to the reappraisal year. The value determined by the Assessor is generally used for the intervening year as well.

Uniform Assessments

After properties have been appraised, the values are analyzed to ensure accurate and equitable assessments. Colorado law requires all Assessors to value property at a specific level and within certain uniformity standards. This provides equity in distribution of state school funding, local tax burden, and assessments that cross county lines.

An independent auditor conducts an annual 1% study of all property in each county. Findings are reported to the State Board of Equalization each year.

Why Property Is Assessed

The property assessment process is the basis for generating property tax revenues that pay for schools, roads, fire protection, police protection, and other local services.

All revenue from property taxes are distributed to taxing entities with in Boulder County. Property tax revenue does not support any state services.

Assessments & Taxes

See How Property Taxes Are Calculated for further information on determining mill levies and figuring property taxes.

Certification to Taxing Authorities

The Assessor certifies, each year in August, the total assessed value of all properties within the boundaries of each Taxing Authority.

  • For non-residential properties, assessed values are calculated by multiplying the actual value by 29%.
  • For residential properties, the assessment percentage is subject to change by the Colorado Legislature each odd-numbered year. The change in percentage is intended to balance the tax burden between residential and all other properties. For the current appraisal period, the residential assessment rate is 7.15% (signed into law June 10, 2019, changing from 7.2%).

Taxing Authorities use these figures to determine their mill levies. If there is any change in the assessed value due to Board of Assessment Appeal decisions, abatements or any other reason, the values are re-certified to the affected Taxing Authorities in early December.

The Mass Appraisal Process

The Assessor uses a mass appraisal process to predict property values. Multiplicative (logarithmic) multiple regression algorithms are derived from the variables in our database, as well as transformed variables that are created to improve the predictive capability of the model. This is done using the statistical software, SPSS.

The results are tested to ensure reasonable accuracy in property valuations.

The State of Colorado audits the outcomes for accuracy and fairness.

Determining Property Value

The Assessor’s Office uses the following methods to determine property value:

  • Evaluation of real market data that reflect actual sales in the marketplace
  • Comparison of properties of “like” characteristics and location using state-of-the-art modeling software and advanced mass property appraisal tools
  • Incorporation of information derived from property appeals

Property Valuation Process

Contact Us

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

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


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Boulder, CO 80306-0471

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