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ACH Notification of Change code

C03 NOC code: Incorrect Routing Number and Incorrect DFI Account Number

An RDFI sends C03 instead of returning an entry it could post but that carried outdated or wrong information. Corrected data: Correct routing number in positions 1–9, blanks in 10–12, correct DFI Account Number in 13–29.

What C03 means

C03 is the change code Incorrect Routing Number and Incorrect DFI Account Number. The entry it answers was posted (or, for a prenotification, accepted); the NOC tells the Originator what to correct before the next one.

  • Both the routing number and the account number changed, typically when an account moved to another institution or system.

What to update, and by when

Replace both the routing number and the DFI Account Number.

The Rules give the Originator six banking days from receiving the NOC information, or until its next entry to the account, whichever is later. NOCs carry no money: the entry they answer settled normally.

The RDFI transmits the NOC within 2 banking days of the settlement date of the original entry; the Originator makes the change within 6 banking days of receiving the NOC information or before its next entry, whichever is later.

Worked example

For an entry that settled on Wednesday, November 25, 2026, the day before Thanksgiving: the RDFI must transmit the NOC by Monday, November 30, 2026.

Try your own settlement date in the ACH date calculator

How C03 appears in a NACHA file

A NOC is a zero-dollar entry in a batch with SEC code COR. Its entry detail record carries a return-type transaction code (21, 26, 31 or 36) and one addenda record of type 98:

Notification of Change addenda record (type 98) with C03
PositionsFieldIn a C03 NOC
1Record Type Code7 (addenda)
2–3Addenda Type Code98 (Notification of Change)
4–6Change CodeC03
7–21Original Entry Trace NumberTrace number of the entry being corrected
22–27ReservedBlank
28–35Original Receiving DFI IdentificationFirst 8 digits of the original entry’s RDFI routing number
36–64Corrected DataCorrect routing number in positions 1–9, blanks in 10–12, correct DFI Account Number in 13–29
65–79ReservedBlank
80–94Trace NumberThe NOC entry’s own trace number

To read a NOC 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 C03 from code or an AI agent

REST · GET · no key
curl -s 'https://payopskit.com/api/v1/codes/C03?set=ach-noc'
MCP · tools/call · lookup_payment_code
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "lookup_payment_code",
    "arguments": {
      "code": "C03",
      "set": "ach-noc"
    }
  }
}
Response (JSON)
{
  "code": "C03",
  "set": "ach-noc",
  "found": true,
  "matches": [
    {
      "set": "ach-noc",
      "code": "C03",
      "name": "Incorrect Routing Number and Incorrect DFI Account Number",
      "description": "Notification of Change. Corrected data: Correct routing number in positions 1–9, blanks in 10–12, correct DFI Account Number in 13–29.",
      "details": {
        "refused": false,
        "retired": false,
        "correctedData": "Correct routing number in positions 1–9, blanks in 10–12, correct DFI Account Number in 13–29",
        "timeframe": "The RDFI transmits the NOC within 2 banking days of the settlement date of the original entry; the Originator makes the change within 6 banking days of receiving the NOC information or before its next entry, whichever is later",
        "timeframeKind": "banking-days",
        "timeframeDays": 2,
        "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.

Source: Nacha Operating Rules, Appendix Five (Notification of Change). The code’s title is the Rules’ own; the rest is this site’s plain-language summary, informational and not a substitute for the Rules or your ODFI agreement.