California Code, Insurance Code - INS § 11665

(a) An insurer who issues a workers' compensation insurance policy to a roofing contractor holding a C-39 license from the Contractors' State License Board shall perform an annual payroll audit for the contractor.  This audit shall include an in-person visit to the place of business of the roofing contractor to verify whether the number of employees reported by the contractor is accurate.  The insurer may impose a surcharge on each policyholder audited under this subdivision in an amount necessary to recoup the reasonable costs of conducting the annual payroll audits.

(b) The commissioner shall direct the rating organization designated as his or her statistical agent to compile pertinent statistical data on those holding C-39 licenses, as reported by the appropriate state entity, on an annual basis and provide a report to him or her each year.  The data shall track the total annual payroll and loss data reported on those holding C-39 licenses in accordance with the standard workers' compensation insurance classifications applicable to roofing operations.  The data shall include the number of employers, total payroll, total losses, and the losses per one hundred dollars ($100) of payroll by the employers' annual payroll intervals as follows:

The report shall also be provided to the Legislature by the commissioner, in compliance with Section 9795 of the Government Code.