Credit Card Verification Number For your security, Starbucks requires that you enter the verification number on your credit card when making a purchase on our website, including Starbucks Card reloads. On Visa, Mastercard, or Discover credit cards, this number consists of the last three digits on the signature strip (see figure A, below). On American Express cards, this number is located on the front of the cards, printed above and to the right of the card number (see figure B, below). figure A - (Visa, MC) figure B - (American Express)    verfication number verification number close window