Vouchers must be filled out by the agency on forms approved by the Comptroller. The vouchers are to be submitted, together with a sample of the job, a purchase order (if the cost is less than the State minimum bid threshold), an original invoice from the vendor, or a payee signature on the voucher with the approved transmittal form and forwarded to the Office of the State Comptroller, Bureau of State Expenditures, Printing Audit Unit.