I am about to start charging customers a credit card conveniency fee.  at the moment the only way to do it is to add a new product code, and then add a new item line on the customer invoice using the product code you created.  Just an example, if you’re charging 3% of the total cost of the invoice, The amount will be entered on the invoice as credit card convenience fee. Unfortunately, this will only be applicable when the customer is paying by credit card, or perhaps Venmo, and Zelle, if you have these set up on your system.  if they decide to pay by check or cash, the convenience fee is no longer relevant and will have to be removed from the invoice with the credit note.  It certainly sounds like a long process in order to charge the customer for using a credit card