Key Controls Test of Control Substantive Test of Transaction 1. Segregation of the purchasing, receiving, and cash disbursements functions. Purchasing, receiving, and a single individual should not control cash disbursements. It could lead to the possibility of fraud. Observation: The auditor can check to see if different people handle all three functions. Controls must be validated. A copy of the purchase invoice, goods receipt note, and cash payment vouchers may be obtained by the auditor to verify if separate people are completing these tasks or not. 2. Use of prenumbered voucher packages, properly accounted for. The use of pre-numbered vouchers precludes transaction backdating and the deletion of a voucher; in the absence of pre-numbered vouchers, a coupon can be withdrawn. Observation: The auditor can check to see if all of the vouchers are pre-numbered. The auditor may get a copy of the vouchers to check for pre-numbering.