Return incomplete forms, send purchase orders, file agreements. Every one is ready to run, and you can adjust it in plain language.
Keep contract requests missing a W-9 out of the approval queue.
Your requesters get a clear W-9 correction email. Their contract tasks wait in your needs-documents section with a comment.
Surface overdue supplier signatures on assigned task lists.
Your procurement owners see unsigned supplier agreements on their task lists after the target signing date passes.