ACH Return Codes

ACH return codes are the standardized messages the receiving bank sends back when a transfer cannot be completed — insufficient funds, a closed account, a customer disputing the authorization, and so on. For merchants, a return is rarely just a failed payment. It triggers fees, disrupts cash flow, and, if return rates drift above NACHA’s thresholds, can put your ability to accept ACH payments in genuine jeopardy. This guide walks through what each code means, what returns actually cost, and where prevention efforts are best directed.