It’s simple to work out transaction fees and how much you will owe at the end of the month, along with other fixed fees you’ll pay your credit card processing provider or merchant. If a customer makes a purchase of £35 and uses their credit card to pay for it, the processer will apply their transaction fee of 1.69% in the case of Sum Up. That’s 0.02p. Some providers will also charge a flat fee per transaction on top such as 20p. That means for this £35 transaction paid for on credit card, you’ll pay 22p in transaction fees.  These fees and costs are a fact when it comes to offering customers the opportunity to pay by credit card, both contactless and by chip and pin. They allow them to pay securely and for you to process the payments securely too.