The Verification Code is imprinted on credit cards to help merchants verify transactions when the actual card is not present, such as Internet purchases or donations. The merchant uses this number as part of the authorization process with the card issuer. Please use the images below to locate the verification code for your card type. Visa and Master Card: The verification code for Visa ,Master Card and Discover is a 3-digit number printed on the back of your card. It appears after the account number or last 4-digits of your account number, in the signature panel. American Express Card: The American Express security code is a 4-digit number printed on the front of your card. It appears after and to the right of your card number.