Efficiently screening ACH items and providing an indicator of the screening result. Electronic files, which can be in the NACHA file format, comprise ACH items. A gateway operator or an originating financial institution can screen each ACH item using a screening software module. For each ACH item, an indicator associated with the screening can be inserted into the ACH file before the ACH item is forwarded to a receiving financial institution. The indicator can identify whether the screening produced a match against an interdiction list and/or whether the screening produced a false positive. If the screening produced a match, processing of the ACH item can be suspended, and the ACH item can be returned to the originating financial institution. Notification of the match can be transmitted to the originating financial institution, the receiving financial institution, and/or law enforcement authorities.