The addition of an external bank card in the application is free.
When adding a card in the application, a request is sent to the issuing bank of that card to activate the 3-D Secure security. This action protects against card theft or unwanted uses.
This security was designed several years ago to protect card transactions on the Internet. To benefit from it, it is mandatory to simulate a transaction. For adding a card, a transaction of €1 is made.
However, this €1 is never charged. It is a card authorization that is requested and then canceled.
A very rarely visible operation
The vast majority of affected customers never see this operation, but some immediate debit cards, such as prepaid cards, notify their customers in real-time of this authorization.
Additionally, some card issuers do not interpret the cancellation of the card authorization and therefore wait up to 10 days to cancel it. During this time, the €1 is blocked but remains in the customer's account.