When multiple charges against an account arrive on the same day, banks usually clear the items according to a set process, such as from the largest amount to the smallest. Sometimes, however, the bank elects to clear items in a different order. To make that happen, it introduces a force pay debit memo that ensures that a particular item will be processed and paid first.
Banks utilize force pay debit memos for various reasons. A bank may elect to process checks cashed at one of its branches first, for example, encoding the checks to ensure that they get settled before other items. Banks also may use force pay debit memos to process items for those who have overdraft protection on their accounts, so that payments are processed even if it temporarily puts an account in the negative.