ACH Return Codes Explained: A Developer's Guide to R01–R85 and Error Handling When a payout fails, the Nacha network doesn't just say "no." It sends back a specific return code—a two-character alphanumeric that tells you exactly why the transaction rejected. As a developer building payment systems, understanding these codes is the difference between a silent failure and a recoverable error. What Are ACH Return Codes? ACH return codes (R01 through R85) are standardized respon...