ACH Return Codes Explained: R01–R85 and How to Handle Them in Production ACH Return Codes Explained: R01–R85 and How to Handle Them in Production When an ACH debit or credit fails, the originating bank receives a return code—a two-character alphanumeric defined by Nacha (the National Automated Clearing House Association). As a developer building payment infrastructure, you need to decode these codes quickly and route the failure appropriately. A mishandled return can orphan a pay...