Abstract: System and methods for countering credit card fraud comprising cardholder changeable card security code CVV2 (also known as CVC2/CID). It enables cardholder to optionally choose a CVV2 different from the one printed on the card, storing/recording it on card issuer database and from then on use it as a secret separate from the card, changing it as needed, for example on being notified of financial institution data breach, or after an online transaction that seemed risky or periodically as a security practice. Fraudulent authorization requests would be rejected when CVV2 submitted does not match cardholder changed value. This system may be implemented with no or modest change in existing credit cards; terminals, equipment, computer software and communication protocols used in transaction authorization. It may facilitate adoption by making cardholders active participants in fraud prevention with modest, optional, easy to comprehend change not tied to each transaction.