You can use most American Express, Mastercard or Visa credit cards. Exceptions include, without limitation, corporate and purchasing cards, Health Savings Account (HSA) cards, Flexible Spending Account (FSA) cards, government-administered prepaid cards (including EBT cards), insurance prepaid cards, Visa Buxx and Apple Credit Cards. Discover cards are not supported currently and there may be other types of cards not listed here that will not be accepted as Linked Cards by the Rewards Site. Only Linked Cards issued in the U.S. are eligible to get Cash Back. The Linked Card must have an account number that is unique to you (i.e., if you share a payment card account with someone else under the same Linked Card account number – the first person that registers that Linked Card will be the one that is able to use it).