Welcome to the Contra Costa County Assessor’s Office. The County Assessor is an elected official and is governed by the California Constitution, the laws passed by the Legislature, and the rules adopted by the State Board of Equalization.  

For online assistance, use the quick links below.


  • Discovering and assessing all property within the County
  • Producing and delivering an assessment roll by July 1 of each year
  • Valuing all real property
  • Auditing all entities doing business in the County and valuing all taxable personal property
  • Establishing and maintaining a set of 11,000 maps for assessment purposes, delineating every parcel of land in the County
  • Providing a public information service to assist taxpayers with questions about property ownership and assessment