A three-bucket policy that survives contact with reality
Most teams try to build a single confidence threshold and end up either drowning in review or quietly accepting errors. Three buckets works better, because it separates "look at this document" from "confirm this one field".
Auto-accept: every deterministic check passes, the document type is routine, and no high-consequence field was flagged. Field verification: one or two specific fields are shown to a person with the source image beside them, and they either confirm or correct. Full review: the document is opened and worked by hand, because something structural failed — the arithmetic does not balance, the document type is unexpected, or the file is unreadable.
The middle bucket is where the leverage is. A reviewer confirming two highlighted fields takes seconds; a reviewer re-reading a whole document takes minutes.