California Code, Labor Code - LAB § 4603.4

(a) The administrative director shall adopt rules and regulations to do all of the following:

(b) To the extent feasible, standards adopted pursuant to subdivision (a) shall be consistent with existing standards under the federal Health Insurance Portability and Accountability Act of 1996.

(c) Require all employers to accept electronic claims for payment of medical services.

(d) Payment for medical treatment provided or prescribed by the treating physician selected by the employee or designated by the employer shall be made with an explanation of review by the employer within 15 working days after electronic receipt of an itemized electronic billing for services at or below the maximum fees provided in the official medical fee schedule adopted pursuant to Section 5307.1. If the billing is contested, denied, or incomplete, payment shall be made with an explanation of review of any uncontested amounts within 15 working days after electronic receipt of the billing, and payment of the balance shall be made in accordance with Section 4603.2.