STATEMENTS. This claim may be used to file for the Homeowners' Exemption for the Assessment Roll and the Supplemental Assessment Roll. How to File a Homestead Exemption.A homeowner must file for the homestead exemption with the correct county recorder's office. Contact your local property appraiser if you have questions about your exemption. Complete the form online and select the state's e-file option. When to file: Application for all exemptions must be made between January 1 and March 1 of the tax year. Contra Costa County.