How to appeal a Contra Costa County, CA property assessment
✓ Verified — Last verified October 24, 2026
Filing details published for Contra Costa County. Match the notice and assessment cycle to the official instructions.
Official appeal instructionsNot tax or legal advice; confirm with your county.
Filing timing
Notice-dependent instructions
Regular appeals: July 2 through November 30 each year. Supplemental or escape assessments: within 60 days of notice.
Official source. Verified .
Where to file
Mail application and $40 check to Assessment Appeals Board, 1025 Escobar Street, 1st Floor, Martinez, CA 94553.
Official source. Verified .
Official offices
Contra Costa County Assessor
Sources for these instructions
https://www.contracosta.ca.gov/2924/Assessment-Appeals
Regular Assessment Appeals must be filed between July 2 and November 30 of each calendar year. Supplemental or Escape assessments must be filed within 60 days of the notice from the Assessor.
Verified October 24, 2026
https://www.contracosta.ca.gov/2924/Assessment-Appeals
Once completed, mail application and $40 check to: Assessment Appeals Board 1025 Escobar Street 1st Floor Martinez, CA 94553
Verified October 24, 2026
https://www.contracosta.ca.gov/2924/Assessment-Appeals
Assessment Appeal Application (PDF)
Verified October 24, 2026
Continue with your property
Common questions
Where do I file a Contra Costa County assessment appeal?
Mail application and $40 check to Assessment Appeals Board, 1025 Escobar Street, 1st Floor, Martinez, CA 94553.
Updated , from cited verification dates. Individual sources may have earlier checks.