a method and apparatus for verification of a voucher after printing by a gaming printer . a human readable validation character string is received by a printer controller for printing on a voucher . a scanned validation character string is read from the voucher using an optical recognition process as the voucher is being printed . the voucher is verified by comparing the received and scanned validation character strings . if the two validation character strings are different , the voucher may be voided by the printer controller before the voucher is finished being printed .