The short answer
An ACH return code is the three-character code (R01 through R99, plus a handful of R99-prefix variants) the receiving depository financial institution (RDFI) returns when it cannot post an ACH entry to the customer's account. The code tells your bank — and by extension your processor and you — why the transaction failed. ACH is not real-time: a transaction can look like it settled on day one and come back as a return on day two through day five.
The codes operators see most
- R01 — Insufficient Funds. The single most common return. Your customer's account did not have enough to cover the debit on the settlement date. You can re-present up to two more times.
- R02 — Account Closed. Do not re-present. Contact the customer for a new account.
- R03 — No Account / Unable to Locate. Routing + account combination does not exist. Often a typo.
- R04 — Invalid Account Number. Account number fails the bank's internal check.
- R07 — Authorization Revoked by Customer. Customer told their bank they no longer authorize you. Hard stop — do not re-debit.
- R08 — Payment Stopped. Customer placed a stop-payment order for this specific item.
- R10 — Customer Advises Unauthorized. The ACH equivalent of a chargeback. Counts against your unauthorized-return threshold.
- R29 — Corporate Customer Advises Not Authorized. Same as R10 for B2B entries.
- R51 — Item Related to RCK (Represented Check) Entry Is Ineligible. Less common; check-conversion only.
NACHA thresholds operators must stay under
- Unauthorized return rate: 0.5% (R05, R07, R10, R11, R29, R51). Breach = origination review, possible suspension.
- Administrative return rate: 3.0% (R02, R03, R04).
- Overall return rate: 15.0%.
Cross these and your ODFI (originating bank) will cap your limits, raise your reserves, or cut you off entirely — same consequence pattern as crossing the VAMP threshold on card rails.
What operators need to know
- Re-present R01 and R09 only. Everything else, go back to the customer. Re-presenting an R07 or R10 is an unauthorized ACH origination and a NACHA violation.
- Watch the lag. ACH returns come back on banking days T+1 through T+5 for most codes, up to T+60 for consumer unauthorized (R10). A subscription that looks healthy today can have a wave of R10s land six weeks later.
- Fees compound. Each return typically costs $2-$5 from your ODFI. Re-presenting a failed $29 subscription three times to recover $29 can cost you $9-$15 in return fees alone.
- Keep the authorization on file. You need the signed or e-signed ACH authorization for two years after termination to defend an R10.
Multi-brand operators running separate merchant accounts per brand need to monitor return rates per brand, not in aggregate — a single bad-list brand dragging the portfolio past 0.5% unauthorized will get every brand suspended on the same ODFI.