(1) No altered or corrected invoice will be accepted for refund purposes when errors occur. The original invoice must not be altered or corrected but must be voided and a new original invoice issued.  All altered or corrected invoices must be marked void and retained by the seller for a period of at least three years from date issued.

(2) Each licensed seller is required to file for approval a completed sample set of invoices that will be issued covering sales to refund applicants.   A sample invoice must be filed annually regardless if the invoice changed.