To set up a new business account to file your Business Property Statement, please call (925) 313-7600 for more information. Access forms available from the Assessor's office, including benefits, business personal property, change in ownership, and other general forms.Please Download PDF BOE-571-S REV. Total of 103 forms are available for Contra Costa County for 2024. Victims of severe winter storms, flooding, and mudslides in California beginning Jan. 8, 2023, now have until Oct. Once forms are filed exemption is automatically renewed each year. Contra Costa County Clerk. Why Join Contra Costa County? "Tax administrator" means the Contra Costa County treasurer-tax collector and his duly appointed deputies.