Cal. Rev. & Tax. Code § 11551

If the board determines that any amount, penalty, or interest has been paid more than once or has been erroneously or illegally collected or computed, the board shall set forth that fact in the records of the board and shall certify the amount collected in excess of the amount legally due and the person from whom it was collected or by whom paid. The excess amount collected or paid shall be credited by the board on any amounts then due and payable from the person from whom the excess amount was collected or by whom it was paid under this part, and the balance shall be refunded to the person, or his or her successors, administrators, or executors. Any proposed determination by the board pursuant to this section with respect to an amount in excess of fifty thousand dollars ($50,000) shall be available as a public record for at least 10 days prior to the effective date of that determination.