In Canada businesses are able to charge 2.4% processing surcharge, for credit card payments. I have it noted on my invoice that this will be applied, however, I'm hoping it can be applied automatically when someone chooses to use that option for payment. So that I don't have to rewrite the invoices when someone chooses to do so. I typically leave the credit card option off, so that they have to ask if they want to pay by credit card. This way I could just leave it on and they can decide at the time of sale.