Cal. Civ. Code § 1809.1

Notwithstanding any contrary provision of this title a financing agency may purchase a retail installment contract or installment account from a seller on such terms and conditions and for such price as may be mutually agreed upon. No filing of notice or of the assignment, no notice to the buyer of the assignment, and no requirement that the seller be deprived of dominion over payments upon the contract or installment account or over the goods if repossessed by the seller, shall be necessary to the validity of a written assignment of a contract or installment account as against creditors, subsequent purchasers, pledgees, mortgagees or encumbrancers of the seller, except as may otherwise be required by law.