Cal. Insurance Code § 900.2

(a) All insurers doing business in this state shall have an annual audit by an independent certified public accountant. The audit, including required auditor and management reporting, the audit committee and its membership, and other aspects of the audit content and process, shall be conducted, and the audit report prepared and filed, in conformity with the standards adopted by the National Association of Insurance Commissioners. (b) The commissioner may grant 30-day extensions of the filing date upon a showing by the insurer and its independent certified public accountant of the reasons for requesting each extension and the determination by the commissioner of substantial cause for an extension. The request for an extension shall be submitted in writing not less than 10 days prior to the due date in sufficient detail to permit the commissioner to make an informed decision on the requested extension. (c) The commissioner may promulgate regulations to further the purposes of this section.