ACH positive pay (also called an ACH debit filter or ACH block) is a bank service that lets a company define which originators are allowed to debit its account — by originator ID, amount limit, and frequency — and blocks or flags any ACH debit outside those rules.

How it works

The company registers approved originators — payroll provider, tax authority, key vendors — with per-originator caps. Anything else becomes an exception for same-day review, and unknown debits default to return.

Setting the rules well

  • Start from 12 months of ACH history to build the allowlist.
  • Cap each originator slightly above its normal maximum.
  • Review the list quarterly alongside vendor-master changes.
  • Treat a request to add a new originator with the same callback verification as a bank-detail change.

Limits

It stops unauthorized pulls, not authorized mistakes — a debit you approved under false pretenses sails through, which is a verification problem, not a filtering one.