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April 28, 2021

Boulder County Assessor to mail real property Notices of Value on May 1

Property owners will receive their biennial Notice of Value from the Assessor’s Office in May. The appeal period runs from May 1 to June 1.

Boulder County, Colo. - The Boulder County Assessor’s Office will send more than 120,000 notices of value to property owners on Saturday May 1.

Every odd year, county assessors in Colorado are required to reassess properties within their jurisdiction and determine the market value for each property as of June 30 of the prior year. Therefore, this year’s reappraisal cycle is based on market values as of June 30, 2020.

Overall in Boulder County, there has been a positive change in values for residential properties. The median percent increases for residential type properties in this appraisal period is 11%.

Maps showing median changes in residential property values from July 1, 2018 – June 30, 2020:


Owners who wish to appeal the determined market value of their home or commercial property are required to file their appeal with the Assessor’s Office by 11:59 p.m. on Tuesday, June 1.

Property owners may appeal their values on the website -- or by fax, by mail, drop box, or email. There are online tools available at to help property owners research comparable sales data and attach that information to their appeal.

COVID-19 restrictions and public service hours

Due to COVID-19 restrictions, the Boulder County Courthouse (including the 2nd floor Assessor's Office) is closed to the public.

  • To schedule a phone call with Assessor’s Office staff, please use the online scheduling tool at or call 303-441-3530 (leave a voicemail message after hours).
  • Please note: The Assessor’s Office’s virtual service hours are 7:30 a.m. – 5 p.m. Monday – Thursday. The office is closed for public-facing services on Fridays.

Notices of Value

All residential property owners will be mailed a three-fold Notice of Value postcard that includes the property’s basic assessment information. Property owners can access a more traditional Notice of Value at Anyone without computer access can call the office at 303-441-3530 to request that a traditional Notice of Value be mailed to them at no charge.