Credit Card Glossary: Terms and Definitions
Over-blocking is a term used to describe what a card issuing bank can do to prevent transactions of an undesired nature, such as online gambling. Similar to how card networks monitor merchant category codes (MCCs) to block charges that don’t comply with network policies or federal regulations, card issuing banks also have similar controls. For example, an issuing bank can decide not to approve a transaction that comes through with an MCC indicating a lottery purchase if they view it as a possible legal liability. This practice may vary between banks so check your cardholder agreement for purchase restriction specifics.