Yes, cash back can expire. The best cash back cards often offer non-expiring rewards, but it’s not a given. With some cards, your rewards might expire after a certain length of time or after an extended period of card inactivity.
Even cards that offer non-expiring rewards typically require the account to still be open in order to access your rewards. In other words, most cards will not allow you to redeem your cash back after you’ve closed your account.
See related: When is the best time to redeem cash back rewards