Ins. Code, § 11735

(a) Every insurer shall file with the commissioner all rates and supplementary rate information that are to be used in this state. The rates and supplementary rate information shall be filed not later than 30 days prior to the effective date. Upon application by the filer, the commissioner may authorize an earlier effective date. To the extent possible, rates and supplementary rate information shall be based upon supporting information derived from the experience or data of the insurer, rating organization, advisory organization, or other insurers. For the purposes of this subdivision, “rating organization” shall have the same meaning as set forth in subdivision (b) of Section 11750.1, and “advisory organization” shall have the same meaning as set forth in subdivision (e) of that section.

(b) Rates filed pursuant to this section shall be filed in the form and manner prescribed by the commissioner. All rates, supplementary rate information, and any supporting information for rates filed under this article, as soon as filed, shall be open to public inspection at any reasonable time. Copies may be obtained by any person upon request and the payment of a reasonable charge.

(c) Upon the written application of the insurer and insured, stating its reasons therefor, filed with the commissioner, a rate in excess of that provided by a filing otherwise applicable may be used on any specific risk.

(d) Notwithstanding Section 679.70, no rating organization may issue, nor may any insurer use, any classification system or rate, as applied or used, that violates Section 679.71 or 679.72 or that violates the Unruh Civil Rights Act.

(e) Notwithstanding Sections 11657 to 11660, inclusive, supplementary rate information filed with the commissioner for purposes of offering deductibles to policyholders for all or part of benefits payable under the policy shall be deemed complete if the filing contains all of the following:

(1) A copy of the deductible endorsement that is to be attached to the policy to effectuate deductible coverage.

(2) Endorsement language that protects the rights of injured workers and ensures that benefits are paid by the insurer without regard to any deductible. The endorsement shall specify that the nonpayment of deductible amounts by the policyholder shall not relieve the insurer from the payment of compensation for injuries sustained by the employee during the period of time the endorsed policy was in effect. The endorsement shall provide that deductible policies for workers’ compensation insurance coverage shall not be terminated retroactively for the nonpayment of deductible amounts.

(3) The endorsement shall provide that notwithstanding the deductible, the insurer shall pay all of the obligations of the employer for workers’ compensation benefits for injuries occurring during the policy period. Payment by the insurer of any amounts within the deductible shall be treated as an advancement of funds by the insurer to the employer and shall create a legal obligation for reimbursements, and may be secured by appropriate security.

(4) The endorsement shall specify whether loss adjustment expenses are to be treated as advancements within the deductible to be reimbursed by the employer.

(5) An explanation of premium reductions reflecting the type and level of the deductible shall be clearly set forth for the policyholder.

(6) The filing shall provide that premium reductions for deductibles are determined before application of any experience modification, premium surcharge, or premium discount, and the premium reductions reflect the type and level of deductible consistent with accepted actuarial standards.

(7) The filing shall provide that the nonpayment of deductible amounts by the insured employer to its insurer, or the failure to comply with any security-related terms of the policy, shall be treated under the policy in the same manner as the payment or nonpayment of the premium pursuant to paragraph (1) of subdivision (b) of Section 676.8.

(f) The insurer shall report and record losses subject to the deductible as losses for purposes of ratemaking and application of an experience rating plan on the same basis as losses under policies providing first dollar coverage.