ACH return reason code
R43 return code: Invalid DFI Account Number
A federal agency rejects an ENR entry with an invalid DFI account number.
What R43 means
R43 is the return reason code Invalid DFI Account Number
. A federal agency rejects an ENR entry with an invalid DFI account number.
It is sent by the Federal Government agency as a return entry: the original entry goes back to the ODFI with an addenda record carrying R43, and the ODFI passes the return on to the Originator.
Typical causes
- A federal agency rejects an ENR entry because the DFI account number is not valid.
Return timeframe
Sent by a Federal Government agency rejecting an enrollment (ENR); timing follows the agency’s processing.
What the Originator can do next
- An ENR entry enrolls a beneficiary in a federal agency’s direct deposit. The financial institution that sent it corrects the field the code names and sends a new enrollment.
- Timing follows the agency’s enrollment processing; the Green Book (the Treasury’s guide to federal ACH payments) has the details.
How R43 appears in a NACHA file
A return is the original entry detail record (type 6) sent back with a return transaction code — 21 or 26 for a checking account, 31 or 36 for savings (21 and 31 return a credit, 26 and 36 a debit) — the original amount, and an addenda record of type 99 that carries the reason. The batch keeps the original entry’s SEC code.
| Positions | Field | In an R43 return |
|---|---|---|
| 1 | Record Type Code | 7 (addenda) |
| 2–3 | Addenda Type Code | 99 (return) |
| 4–6 | Return Reason Code | R43 |
| 7–21 | Original Entry Trace Number | Trace number of the entry being returned |
| 22–27 | Date of Death | YYMMDD for R14 and R15; blank otherwise |
| 28–35 | Original Receiving DFI Identification | First 8 digits of the original entry’s RDFI routing number |
| 36–79 | Addenda Information | Free text from the RDFI |
| 80–94 | Trace Number | The return entry’s own trace number |
To read a return file record by record, open the file in NACHA Navigator, a free sister site that parses NACHA files in your browser without uploading them.
Look up R43 from code or an AI agent
The code table on this page is the one behind the REST API and the MCP server, so a script or an AI agent gets the same answer as JSON. No key and no account.
curl -s 'https://payopskit.com/api/v1/codes/R43?set=ach-return'{
"jsonrpc": "2.0",
"id": 1,
"method": "tools/call",
"params": {
"name": "lookup_payment_code",
"arguments": {
"code": "R43",
"set": "ach-return"
}
}
}{
"code": "R43",
"set": "ach-return",
"found": true,
"matches": [
{
"set": "ach-return",
"code": "R43",
"name": "Invalid DFI Account Number",
"description": "A federal agency rejects an ENR entry with an invalid DFI account number.",
"details": {
"category": "return",
"timeframe": "Sent by a Federal Government agency rejecting an enrollment (ENR); timing follows the agency’s processing",
"timeframeKind": "not-defined",
"timeframeDays": null,
"timeframeFrom": null,
"account": "any",
"accountNote": null,
"writtenStatement": false,
"initiatedBy": "Federal Government agency",
"note": "ENR only",
"effectiveFrom": null,
"upcomingChange": null,
"caveat": "ENR returns are governed by the federal agency’s enrollment processing; confirm timing in the Rules and the Green Book."
}
}
]
}The MCP server is at /mcp (Streamable HTTP, no key); the API and MCP docs show how to connect Claude, Cursor or VS Code.
The deadline for a settlement date: GET /api/v1/ach/return-deadline?settlement_date=2026-11-25&code=R43 or the MCP tool ach_return_deadline.
Source: Nacha Operating Rules, Appendix Four (Return Entries). The code’s title is the Rules’ own; the rest is this site’s plain-language summary. It is informational and not a substitute for the Rules, your ACH Operator’s schedule or your ODFI agreement.