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How to Activate a Costco Mastercard

Your activation code will be sent to you via email with instructions on how to activate your card once it arrives in the mail. Here’s an overview of the steps:

  1. When you have both your activation code and your card, call the number found on the sticker on the front of your card (1-800-945-1000).
  2. When you call, you’ll be asked to enter both your activation code and your card number.
  3. You’ll set up your personal identification number (PIN) by following the prompts.