California Code, Revenue and Taxation Code - RTC § 46401

(a) The board, whenever it determines it to be necessary to ensure compliance with this part, may require any person subject to this part to place with it such security as the board may determine to be reasonable, taking into account the circumstances of that person. Any security in the form of cash, government bonds, or insured deposits in banks or savings and loan institutions shall be held by the board in trust to be used solely in the manner provided by this section. The board may sell the security at public auction if it becomes necessary to do so in order to recover any fee or any amount required to be collected, including any interest or penalty due. Notice of the sale shall be served upon the person who placed the security personally or by mail.

(b) If service is made by mail, service shall be addressed to the person at his or her address as it appears in the records of the board. Service shall be made at least 30 days prior to the sale in the case of personal service, and at least 40 days prior to the sale in the case of service by mail. Security in the form of a bearer bond issued by the United States or the State of California which has a prevailing market price may, however, be sold by the board at private sale at a price not lower than the prevailing market price thereof. Upon any sale, any surplus above the amounts due shall be returned to the person who placed the security.