Cal. Code of Civil Procedure § 700.100

(a) To levy upon chattel paper, the levying officer shall: (1) If the chattel paper is in the possession of the judgment debtor, take the chattel paper into custody. (2) If the chattel paper is in the possession of a third person, personally serve a copy of the writ of execution and a notice of levy on the third person. (b) If the levying officer obtains custody of the chattel paper or if pursuant to a security agreement the judgment debtor has liberty to collect or compromise the chattel paper or to accept the return of goods or make repossessions, the levying officer shall, if so instructed by the judgment creditor, serve a copy of the writ of execution and a notice of levy on the account debtor. Service shall be made personally or by mail. (c) In addition to any other rights created by a levy on chattel paper, the levy creates a lien on the judgment debtor’s rights in specific goods subject to the chattel paper.