Article 62 of the revised EU Payment Services Directive (PSD2) contains a prohibition on surcharging - the practice where a merchant charges an extra fee for receiving a payment made using a payment card. That Article provides that a payee shall not request charges for the use of a payment instrument for which interchange fees are regulated under Chapter II of the EU Interchange Fee Regulation (Regulation (EU) 2015/751.
PSD2 was transposed into Irish law by the European Union (Payment Services) Regulations 2018 (S.I. No. 6 of 2018) and Regulation 86 of the transposing Regulations gives effect to this prohibition, meaning that a merchant cannot surcharge on the vast majority of consumer credit and debit cards including Visa and Mastercard branded cards. The legislation does not allow for exceptions on the basis of the value of the card transaction.
It should be noted that the prohibition on surcharging does not cover transactions with commercial cards or transactions with payment cards issued by three-party payment card schemes. Where surcharges are allowed, the European Union (Payment Services) Regulations 2018 provide that they must not exceed the direct costs borne by the payee to accept the card.