For the first year of filing, a Certification of Disability for Homestead Exemption, Form 458B (available from the county assessor). A homeowners' exemption may also apply to a supplemental assessment.For more information, call (925) 313-7481. STATEMENTS. This claim may be used to file for the Homeowners' Exemption for the Assessment Roll and the Supplemental Assessment Roll. How to Apply for Homestead Exemptions Homestead applications must be filed with the county assessor after February 1, and on or before June 30 of each year. Homestead exemption applications must be filed annually between February 2 and June 30. Application forms are typically available beginning February 2. Total of 103 forms are available for Contra Costa County for 2024.