Internal Control Procedure Control Activity Assertion 1.Two signatories are required on every cheque. 2. Overtime work must be approved by the employees' supervisor. 3. All vendor invoices must be stamped 'Paid' on payment. 4. Sales ledger personnel make postings to only the sales ledger. 5. Only warehouse personnel are allowed in the computer room. 6. Pre-numbered sales invoices are used in invoicing