What is the CID code?

The CID code is a 3- or 4-digit value printed on the card or signature strip, but not encoded on the magnetic stripe.

MasterCard, Visa and Discover credit and debit cards have a 3-digit code. It is not embossed like the card number, and is always the final group of numbers printed on the back signature panel of the card.

American Express cards have a 4-digit code printed on the front side of the card above the number. It is printed flat, not embossed like the card number.