Understanding the Base Period


Colorado law limits the time period that can be used in considering comparable sales to derive a value for a property. This time period is  known as the "base period" or the "data gathering period." Sales of comparable properties that occur after the end of the base period cannot be considered.

Base Period Examples

For example, the only comparable sales that can be used to derive the value of a property for the tax year 2023 are sales that occurred from January 1, 2021 through June 30, 2022, unless a contract for the subject property was executed before this date. If insufficient data is available, comparable sales that occurred before January 1, 2021 may be used in 6-month increments going back no  more than 5 years. Comparable sales that occurred after June 30, 2022 cannot be utilized. Also, for purposes of this example, a property is valued based on its condition as of January 1, 2023.

This example applies only to valuation of a property for tax year 2023. A different base period may apply to valuation of a property by a county for a different tax year.

This document is for general informational purposes only and is not intended to be used as legal advice. The Board of Assessment Appeals cannot provide legal advice. Specific questions should be directed to the applicable county assessor's office.


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