Transactions can be refused by the issuing bank for a number of reasons. This can be due to a lack of funds. As part of the payment authorization process, issuers verify that the consumer has sufficient funds in their account to cover the transaction. Another common reason is that information is incorrect, such as the CVV (Card Verification Value) or address not matching the card’s details. This typically happens as the result of the wrong details being entered at checkout. Transactions can also be refused to prevent fraud. For example, if a card has been reported as lost or stolen, the transaction will not be accepted. The same also applies to cards that have expired.  A transaction may be refused if it is flagged as “unusual activity”. This often affects international transactions where the card is used in another country or shopping in suspicious areas.