Based on the provided content, there is no specific mathematical formula or step-by-step calculation provided for determining a workers compensation premium in California. The information focuses primarily on the claims process for injured workers rather than the detailed financial auditing process for employers.

However, the text mentions that premiums are influenced by certain industry factors and regulatory benchmarks, including:

• Advisory pure premium rates and insurer rates, which are explained by the Workers Compensation Insurance Rating Bureau of California (WCIRB).
• Misunderstandings or misapplications of these advisory pure premium rates can complicate interactions between employers and insurers.
• Insurers typically evaluate claims and respond within 14 days, a process that is influenced by established workers compensation insurance rates in California.

For specific premium calculations, the content suggests referring to WCIRB industry benchmarks and official California Department of Industrial Relations guidance.