Thank you for the responses to my original question. From what I have learned, there may be a legal issue in some states with charging customers credit card fees. However, if it is listed as an option, clearly stating the fees to be charged.... I think this would be legal? 

Again, I have received invoices where I have the option to pay with a credit card with the understanding that I'll pay a fee for this convenience. If it is legally feasible for Quickbooks to have this feature, it would be great.

Leslie