California Code
CHAPTER 4.3 - The Accounts Receivable Management Act
Section 16583.1.

16583.1. A participant may impose a reasonable fee, not to exceed the actual costs, to recover the participant’s collection costs on a past due account.

(Added by Stats. 2009, 4th Ex. Sess., Ch. 23, Sec. 13. Effective July 28, 2009.)