Cal. Rev. & Tax. Code § 7895

If upon the sale the moneys received exceed the amount of all taxes, penalties, interest, and costs due the state from the supplier, the Controller shall return the excess to the supplier and obtain a receipt. If for any reason the receipt of the supplier is not available, the Controller shall deposit the excess moneys in an unclaimed property account, in trust for the supplier, subject to the order of the supplier, the supplier’s heirs, successors, or assigns.