Lab. Code, § 4622

All medical-legal expenses for which the employer is liable shall, upon receipt by the employer of all reports and documents required by the administrative director incident to the services, be paid to whom the funds and expenses are due, as follows:

(a) (1) Except as provided in subdivision (b), within 60 days after receipt by the employer of each separate, written billing and report, and if payment is not made within this period, that portion of the billed sum then unreasonably unpaid shall be increased by 10 percent, together with interest thereon at the rate of 7 percent per annum retroactive to the date of receipt of the bill and report by the employer. If the employer, within the 60-day period, contests the reasonableness and necessity for incurring the fees, services, and expenses using the explanation of review required by Section 4603.3, payment shall be made within 20 days of the service of an order of the appeals board or the administrative director pursuant to Section 4603.6 directing payment.

(2) The penalty provided for in paragraph (1) shall not apply if both of the following occur:

(A) The employer pays the provider that portion of his or her charges that do not exceed the amount deemed reasonable pursuant to subdivision (e) within 60 days of receipt of the report and itemized billing.

(B) The employer prevails.

(b) (1) If the provider contests the amount paid, the provider may request a second review within 90 days of the service of the explanation of review. The request for a second review shall be submitted to the employer on a form prescribed by the administrative director and shall include all of the following:

(A) The date of the explanation of review and the claim number or other unique identifying number provided on the explanation of review.

(B) The party or parties requesting the service.

(C) Any item and amount in dispute.

(D) The additional payment requested and the reason therefor.

(E) Any additional information requested in the original explanation of review and any other information provided in support of the additional payment requested.

(2) If the provider does not request a second review within 90 days, the bill will be deemed satisfied and neither the employer nor the employee shall be liable for any further payment.

(3) Within 14 days of the request for second review, the employer shall respond with a final written determination on each of the items or amounts in dispute, including whether additional payment will be made.

(4) If the provider contests the amount paid, after receipt of the second review, the provider shall request an independent bill review as provided for in Section 4603.6.

(c) If the employer denies all or a portion of the amount billed for any reason other than the amount to be paid pursuant to the fee schedules in effect on the date of service, the provider may object to the denial within 90 days of the service of the explanation of review. If the provider does not object to the denial within 90 days, neither the employer nor the employee shall be liable for the amount that was denied. If the provider objects to the denial within 90 days of the service of the explanation of review, the employer shall file a petition and a declaration of readiness to proceed with the appeals board within 60 days of service of the objection. If the employer prevails before the appeals board, the appeals board shall order the physician to reimburse the employer for the amount of the paid charges found to be unreasonable.

(d) If requested by the employee, or the dependents of a deceased employee, within 20 days from the filing of an order of the appeals board directing payment, and where payment is not made within that period, that portion of the billed sum then unpaid shall be increased by 10 percent, together with interest thereon at the rate of 7 percent per annum retroactive to the date of the filing of the order of the board directing payment.

(e) (1) Using the explanation of review as described in Section 4603.3, the employer shall notify the provider of the services, the employee, or if represented, his or her attorney, if the employer contests the reasonableness or necessity of incurring these expenses, and shall indicate the reasons therefor.

(2) The appeals board shall promulgate all necessary and reasonable rules and regulations to insure compliance with this section, and shall take such further steps as may be necessary to guarantee that the rules and regulations are enforced.

(3) The provisions of Sections 5800 and 5814 shall not apply to this section.

(f) Nothing contained in this section shall be construed to create a rebuttable presumption of entitlement to payment of an expense upon receipt by the employer of the required reports and documents. This section is not applicable unless there has been compliance with Sections 4620 and 4621.