I’m being asked to sign up for an Amex true cash back card...one year ago I did not activate it, what will happen if I activate it now?

Not sure if the activation is still valid after a year. Why not give the customer service a call and see if the card is still usable?

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As long as your cc application is approved, your credit card account is open even if your physical card is not activated. If the card has an annual fee, you may be liable to pay it. Amex might have a set number of days to activate your physical card. If you do not activate it within the set days, your card will be deactivated and you must request for a replacement. Best is to call up the bank to verify.