ACH return reason code

R81 return code: Non-Participant in IAT Program

The Gateway or the foreign institution does not take part in the IAT program for this entry.

What R81 means

R81 is the return reason code Non-Participant in IAT Program. The Gateway or the foreign institution does not take part in the IAT program for this entry.

IAT entries.

It is sent by the Gateway or RDFI as a return entry: the original entry goes back to the ODFI with an addenda record carrying R81, and the ODFI passes the return on to the Originator.

Typical causes

The Gateway or the foreign receiving institution does not take part in the IAT program for this entry.

Return timeframe

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.

Worked example

For an entry that settled on Wednesday, November 25, 2026, the day before Thanksgiving: must be available to the ODFI by opening of business on Monday, November 30, 2026.

Try your own settlement date in the ACH date calculator

What the Originator can do next

Check the IAT addenda (the foreign receiving institution’s identification, names and addresses) with your ODFI and its Gateway before sending again.

How R81 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.

Return addenda record (type 99) with R81
Positions	Field	In an R81 return
1	Record Type Code	7 (addenda)
2–3	Addenda Type Code	99 (return)
4–6	Return Reason Code	`R81`
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

Returns of IAT entries use the IAT version of the return addenda; check its layout in the Rules.

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 R81 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.

REST · GET · no key

curl -s 'https://payopskit.com/api/v1/codes/R81?set=ach-return'

MCP · tools/call · lookup_payment_code

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "lookup_payment_code",
    "arguments": {
      "code": "R81",
      "set": "ach-return"
    }
  }
}

Response (JSON)

{
  "code": "R81",
  "set": "ach-return",
  "found": true,
  "matches": [
    {
      "set": "ach-return",
      "code": "R81",
      "name": "Non-Participant in IAT Program",
      "description": "The Gateway or the foreign institution does not take part in the IAT program for this 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": "IAT entries.",
        "writtenStatement": false,
        "initiatedBy": "Gateway or RDFI",
        "note": "IAT only",
        "effectiveFrom": null,
        "upcomingChange": null,
        "caveat": null
      }
    }
  ]
}

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=R81 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.