Leave the check number blank if you want to print a check.
Enter a number only if the check has already been written. This will ensure a second check is not written to the vendor, by printing the word "DUPLICATE" on the check. You can enter any number, using up to 20 alphanumeric characters.
Note: If you're not paying with a check, enter a reference number that you can use to identify the transaction. On the Payments screen, the field is called Check/Reference Number.
If the Electronic Payment box is selected for this payment, the Check Number box will read "Electronic" since there will be no check number for a payment handled electronically.