R24 return code: Duplicate Entry

R24 is the return reason code Duplicate Entry. The RDFI already received what looks like the same entry.

It is sent by the RDFI as a return entry: the original entry goes back to the ODFI with an addenda record carrying R24, and the ODFI passes the return on to the Originator.

• The RDFI received what looks like the same entry twice: same account, amount and identifying details.
• A batch or a whole file was sent twice.

Available to the ODFI by opening of business on the 2nd banking day after the settlement date of the original entry.

Banking days are the Federal Reserve’s business days: weekends and Fed holidays don’t count, so a holiday in the window pushes the deadline out by a day.

• Check whether the batch or file was transmitted twice.
• If a whole file went out twice, the Rules let the Originator reverse the duplicate within 5 banking days of its settlement date.

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.

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.

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/R24?set=ach-return'

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "lookup_payment_code",
    "arguments": {
      "code": "R24",
      "set": "ach-return"
    }
  }
}

{
  "code": "R24",
  "set": "ach-return",
  "found": true,
  "matches": [
    {
      "set": "ach-return",
      "code": "R24",
      "name": "Duplicate Entry",
      "description": "The RDFI already received what looks like the same entry.",
      "details": {
        "category": "return",
        "timeframe": "Available to the ODFI by opening of business on the 2nd banking day after the settlement date of the original entry",
        "timeframeKind": "banking-days",
        "timeframeDays": 2,
        "timeframeFrom": "original-settlement",
        "account": "any",
        "accountNote": null,
        "writtenStatement": false,
        "initiatedBy": "RDFI",
        "note": null,
        "effectiveFrom": null,
        "upcomingChange": null,
        "caveat": null
      }
    }
  ]
}

The deadline for a settlement date: GET /api/v1/ach/return-deadline?settlement_date=2026-11-25&code=R24 or the MCP tool ach_return_deadline.

• R06Returned per ODFI's Request
• R17Questionable or Improper Entry
• R67Duplicate Return

All ACH return codes, R01 to R85