California Code, Revenue and Taxation Code - RTC § 12984

(a) If the board determines that any overpayment has been made intentionally or made not incident to a bona fide and orderly discharge of a liability reasonably assumed by the insurer or surplus line broker to be imposed by law, no interest shall be allowed on the overpayment.

(b) If any insurer or surplus line broker which has filed a claim for refund requests the board to defer action on its claim, the board, as a condition to deferring action, may require the claimant to waive interest for the period during which the insurer or surplus line broker requests the board to defer action on the claim.

(c) This section shall become operative on July 1, 2013.