The zip code on a credit card is the security measure used to confirm that the card owner is using it.This zip code credit card is anchored to the five-digit postal code of the billing address where you receive your card information.. Most credit cards do not require a PIN for purchase confirmation, which may detract from the product’s security because of the nonexistent credit card zip code. A credit card postal code is the ZIP code associated with a credit card’s billing address. That’s the address you provided on your application, unless you’ve since moved and updated your information. And it’s where you receive your statement every month, if you haven’t gone paperless. A credit card postal code is an additional form of security used to verify it is being used by the owner of the card or an authorized user. It is connected to the five digit zip code for the billing address of the cardholder. JGLev.