Credit Card ID Number In order to protect our customers, the Card Identification Number (Card ID) is required for American Express, Visa and MasterCard purchases for credit card orders. The Card ID is an added security feature to help protect you against online fraud. The Card Identification Number is the group of numbers immediately following your credit card number. These numbers are used by your credit card company to help prevent fraud. Because the Card ID number is not printed on your receipts, it helps ensure that someone is not using your credit card information fraudulently. Note: The digits are printed on your card, rather then stamped in the plastic like the digits in your credit card number. American Express 4 digits on front of card Visa and Mastercard last 3 digits on back of card