California Code, Insurance Code - INS § 10178.5

(a) Every self-insured employee welfare benefit plan issued, amended, or renewed on and after January 1, 1987, that offers coverage for medical transportation services, shall contain a provision providing for direct reimbursement to any provider of covered medical transportation services if the provider has not received payment for those services from any other source.

(b) Subdivision (a) shall not apply to any transaction between a provider of medical transportation services and a self-insured employee welfare benefit plan if the parties have entered into a contract providing for direct payment.

(c) For purposes of this subdivision, “direct reimbursement” means the following:

The insured shall file a claim for the medical transportation service with the plan;  the plan shall pay the medical transportation provider directly;  and the medical transportation provider shall not demand payment from the insured until having received payment from the plan, at which time the medical transportation provider may demand payment from the insured for any unpaid portion of the provider's fee.