ACH Debit Block

An ACH debit block is a service, offered by US banks mainly to business customers, that prevents ACH debits from posting to an account. In its strictest form the bank returns every incoming debit; in more flexible forms, often called an ACH filter, the customer lists approved originators by company ID, sometimes with maximum amounts, and only those debits are allowed through. Blocked entries are sent back to the originator's bank as ACH returns, usually as unauthorized. Companies use debit blocks to protect accounts whose numbers are widely known, such as accounts printed on cheques or invoices, and to stop fraudsters who set up debits with stolen account details. Credits still arrive normally. For more control, a business can combine a block with ACH positive pay, which lets it review exceptions each day before they are paid or returned.