Systems and methods for performing preauthorization of check transactions are disclosed. In some check transactions such as ACH card transactions, the actual purchase amount is not known when the card is first presented to a merchant. Dispensing of gasoline for a fill-up is an example of such a transaction. Various embodiments of the systems and methods disclose preauthorizing such transaction before the actual purchase amount is known, and without placing a hold of the checking account corresponding to the card. In one embodiment, such preauthorization can be based on, for example, a likely purchase amount associated with the merchant. The actual amount, once determined, can be matched with the information used for preauthorization in various manners.