How can I add a credit card use surcharge to my invoice so that I am receiving the full amount and the client is paying for the convenience of using a credit card?

Hello,

You need to be VERY careful about this as not only is it talked about in the merchant agreement with Intuit.  https://quickbooks.intuit.com/payments/legal/TOC102017/merchant-agreement/  But also illegal in some states.  I posted a picture with the info from the agreement below outlined.

Also keep in mind, if you add an additional fee to the invoice, then the feel will be calculated on that additional amount as well.

Ex:  100 invoice paid online.  Fee would be $2.90 + .25 = $3.15

        105 invoice (you add a fee) paid online.  Fee would be $3.05 + .25 = $3.30