The person who is to collect and receive the assessments before the issuance of bonds may be bonded in favor of the entity conducting the proceedings in an amount to be fixed and such bond approved by the legislative body of the entity. When he is a bonded official his services in receiving the money are a duty imposed upon him by law within the purview of his bond. In the case of a county official collecting for a public corporation, the county shall collect any money due on the bond as agent for the public corporation. If the legislative body designating the bonded person finds that his official bond is inadequate it may provide that he shall be separately bonded. The premium of such bond shall be an incidental expense of the proceeding.