California Code, Revenue and Taxation Code - RTC § 50150.5

(a) Notwithstanding any other provision of this part, if the department finds that neither the person liable for payment of fees nor any party related to that person has in any way caused an erroneous refund for which an action for recovery is provided under Section 50150, no interest shall be imposed on the amount of that erroneous refund until 30 days after the date on which the department serves a notice of determination for repayment of the erroneous refund to the person. The act of filing a claim for refund shall not be considered as causing the erroneous refund.

(b) This section shall be operative for any action for recovery under Section 50150 on or after January 1, 2000.