Activating your credit card is a way to let the card issuer know you've received the card. You may not be able to use a card that hasn't been activated. If you don't activate your credit card after a certain amount of time, you may have to request a new card from the credit card issuer. You can still be charged an annual fee if your card has one. Failing to pay the annual fee could lead to a missed payment, late fee, and credit score damage. Finally, the account may eventually be closed for inactivity.