No charges for credit or debit cards
Charges should no longer be made for using a debit or credit card
Retailers could once charge a sum for use of a card, so long as they made this clear. More recently they could only pass on the additional costs of someone using a card. From 13 January 2018, it is illegal to charge anything.
However, a retailer can still set a minimum amount for someone to be able to use credit or debit cards.
This applies whether the purchase was made online or face to face. If a charge is made for an online transaction using a typical card, it is likely that the retailer is breaking the law, or that they are based outside Europe, and do not want to comply with this measure to protect consumers.
There are also some exceptions relating to cards issued outside of Europe. But these are so complicated, and the cards so uncommon, it is not worth a typical retailer’s time to create a sign explaining these exceptions.
The situation for retailers is simple: do not charge for use of a card, and you will stay on the right side of the law.