Cal. Bus. & Prof. Code § 10233.1
If a real estate broker in servicing a real property sales contract or a promissory note secured directly or collaterally by a lien on real property for the mortgagee, beneficiary, or owner of the note or contract, causes funds other than funds received from the obligor of the note or contract to be applied toward a payment to protect the security of the note or contract being serviced, including the payment of debt service on an obligation secured by the same real property having priority over the mortgage or deed of trust securing the promissory note that the broker is servicing, the broker shall, not later than 10 days after making any such payment, give written notice to the mortgagee, beneficiary, or owner of the date and amount of payment, the name of the person to whom payment was made, the source of funds, and the reason for making the payment.
Ca. Bus. and Prof'l. Code § 10233.1