California Code, Business and Professions Code - BPC § 9855.6

Where a service contractholder cancels a service contract in accordance with Section 1794.41 of the Civil Code and the refund due is not paid to the service contractholder or credited to his or her account within 30 days after the service contractor receives written notice of cancellation, the amount of the required refund or credit shall bear interest, payable to the service contractholder, at the rate of 10 percent per annum for each additional 30 days or fraction thereof.