The Rental Housing Management Business Law of 2021 mandates that security deposits be segregated. However, only a simple separate accounting is allowed for the segregated management method. I consider such a method to be inadequate. Therefore, I have considered a method of complete segregation of security deposits with reference to the German system of security deposits. I have considered how to fully protect the security deposit to be returned to the lessee in the event of bankruptcy of the lessor or property manager.