Bidders are required to have a card on file when they bid. We do this to ensure that all bids are real and to streamline the end of auction payment process for the nonprofit. That said, at the end of the auction, you have the option to not charge a user’s credit card. (For example, if an individual reaches out to say that they would prefer to pay by check). We leave this up to you, though we generally recommend against it, as it introduces new complexities to collecting payments.