James Allman | JA Technology Solutions LLC
ACH Return Code Lookup
Look up Nacha ACH return reason codes (R01 to R85) and notification of change codes: what each means, who returns it, and the return window.
ACH Return Code Lookup
Search the full set of Nacha ACH return reason codes by code or by description. Type R01, r10, or even a bare 16 and the lookup normalizes it; type a phrase like insufficient funds and it searches the descriptions. Each code shows a plain-language explanation of what happened, who sends the return (the RDFI, the ODFI, the ACH operator, or a federal agency), the return window where it is well established, and a category so related codes group together: funds, account, authorization, data, government enrollment, and international. The notification of change codes (C01 to C14) are covered in their own section, since a NOC is a correction request rather than a return. With an empty search, the most commonly hit codes surface first. Copy any code with one click. Runs entirely in your browser.
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What ACH Return Codes Are and Who Issues Them
When an ACH payment cannot post, the receiving bank (the RDFI) sends it back through the network with a return reason code, R01 through R85, defined in the Nacha operating rules. Most returns come from the RDFI, but some come from elsewhere: format edits like R26 and R28 are rejected by the ACH operator before they ever reach a bank, R06 returns happen at the originating bank's request, the R40s apply only to federal agency enrollments, and the R80s apply only to international (IAT) entries. The code is the routing instruction for what happens next: an R01 might be retried in a few days, an R02 means stop and get new account details, and an R10 means stop immediately and resolve the authorization question.
Returns Versus Notifications of Change
A notification of change (NOC, codes C01 to C14) is not a return. The payment posted, but the receiving bank is telling the originator to fix a field before the next one: an account number after a bank merger (C02), a transaction code pointed at the wrong account type (C05). Originators are expected to apply the correction, and ignoring NOCs tends to turn into actual returns later. Operationally the two streams need different handling, which is why this lookup keeps them in separate sections.
The Two-Day and Sixty-Day Windows
Most returns travel fast: the standard deadline puts a routine return in the originator's hands within about two banking days of settlement. The big exception is the extended window for consumer authorization claims (codes like R05, R07, R10, and R11), which generally runs 60 calendar days. The practical consequence for anyone originating debits is that a batch is not truly settled when the two-day window closes; an authorization dispute can still arrive weeks later. Corporate accounts work differently: an R29 from a business receiver carries the short window, which is why debit blocks and filters matter so much on commercial accounts. The exact deadlines have qualifications, so treat these as orientation and check the current rules for edge cases.
From Looking Up Codes to Processing Return Files
Returns arrive as records inside a Nacha-format file, and working them by hand does not scale past a handful a day. The NACHA/ACH File Explorer opens those files in the browser and shows every batch, entry, and addenda. When the volume justifies it, I build return processing that matches each return to its original payment, applies per-code retry-or-stop rules, and posts results downstream. See integration services or data pipelines and ETL.
All tools run entirely in your browser. Your data never leaves your machine.