(1) Notifications and authorizations for medical services (either the originals, if available, or copies thereof) shall be maintained on file in the public welfare agency in such a manner as to facilitate audit. If the notification and authorization constitute separate documents, each notification and the authorization relative to it shall be filed together.

(2) Paid bills for medical services shall be maintained on file by the public welfare agency in a manner to facilitate audit and shall be filed in voucher number sequence, or in sequence as listed on the payment rolls.