Enter a creditors adjustment up for the amount of the fee to the required general ledger account using tax code G, then enter and apply the payment for the invoices along with the fee:
▪calculate the fee
▪add a creditors adjustment up for the amount of the fee
▪enter the total amount being paid and apply to the invoice(s) and the creditors adjustment.
Further information
Apply a Credit Card Charge Using Stock
Credit Card Surcharge Management