Signature on the card is required in the regulations between the bank and the card holder. An unsigned card is invalid, and the seller cannot accept the card. Failure to sign the card is dangerous to its holder, because it creates a risk that the card is signed and used by an unauthorized person until its cancellation. If the seller receives an unsigned card, the seller should ask the buyer to sign it, produce an identity document and verify the signature and the details on the card against the document produced (in accordance with Article 9 of the Act on Electronic Payment Instruments). If the card holder refuses to sign the card, the seller cannot accept the payment.