Cal. Veh. Code § 34633

Every motor carrier of property with a carrier fleet of 20 or more commercial motor vehicles as defined in Section 34601 shall, under oath, file annually a report with the department indicating the number, classification, and compensation of all employees and owner-operator drivers hired or engaged during the reporting period. The department shall submit a copy of the report to the administrator of the corporation’s workers’ compensation self-insurance plan if the corporation is self-insured, or to the carrier’s workers’ compensation insurer if the carrier’s workers’ compensation protection is provided by a policy or policies of insurance.