ISO 20022 reason codes: why a payment was rejected, returned or recalled

Four lists, four places

ISO 20022 keeps its reason codes in external code lists, published separately from the messages so they can grow without a new message version. The same code often belongs to several lists: AC04 (closed account) can reject a payment, come back on a return and refuse a recall.

A reason code explains a status or an action; it never stands alone. In a pain.002 read it with the status next to it (see the payment status codes): RJCT plus AC01 means the payment was refused because the account number is wrong. On a camt.053 the returned entry itself tells you the money is back.

Account problems (AC, AG)

The account is wrong, closed, blocked or of a type that cannot take the payment.

Amount and currency (AM, CURR)

The amount is zero, too high, too low, blocked, in the wrong currency or not what was agreed, or the funds are not there.

Party details (BE)

A name, address or identification of the payer, the payee or the initiating party is missing or does not match.

Banks and routing (RC, CNOR, DNOR, AGNT)

A bank identifier is wrong, or a bank cannot be reached through the clearing system used.

Dates and cut-off times (DT, TM)

A requested date is invalid, or the instruction arrived too late.

Duplicates (DU, AM05, DUPL)

A message, block, transaction or reference was seen before.

Direct debit mandates and refunds (MD, SL)

The direct debit has no valid mandate, the debtor asked for a refund, or the debtor’s bank blocked it.

Regulatory (RR)

Information the law requires is missing, or the payment was stopped by compliance checks.

File format and settlement (FF, ED)

The file could not be processed, or settlement between the banks failed.

Reason not given (MS, NARR)

A customer or a bank declined to give a coded reason, or wrote it as text.

Cancellations, recalls and their answers

Why a payment is recalled or cancelled, why funds come back after a recall, and why a recall is refused.

A code that is not on this page

These are the codes banks commonly send, not the complete lists: ExternalStatusReason1Code alone holds well over a hundred codes, and market practices add their own usage rules. The viewers show any other code as written, and the full lists are published with the ISO 20022 external code sets.

Look up a reason code from a script or an AI agent

The same explanation is available to scripts and AI agents, keyless: the REST endpoint GET /api/v1/explain and the explain_code tool of the MCP server at https://iso20022-navigator.com/mcp (API and MCP docs; add it to Claude, Cursor or VS Code).

curl -s 'https://iso20022-navigator.com/api/v1/explain?code=AC04&kind=status_reason'

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "explain_code",
    "arguments": {
      "code": "AC04",
      "kind": "status_reason"
    }
  }
}

{
  "query": "AC04",
  "kind": "status_reason",
  "matches": [
    {
      "kind": "status_reason",
      "code": "AC04",
      "name": "Closed account number",
      "definition": "The account is closed.",
      "usedIn": "pain.002 / pacs.002 StsRsnInf/Rsn/Cd; pacs.004 RtrRsnInf/Rsn/Cd; camt.053/054 TxDtls/RtrInf/Rsn/Cd; camt.029 CxlStsRsnInf/Rsn/Cd",
      "reference": "https://iso20022-navigator.com/iso20022-reason-codes/ac04"
    }
  ]
}