IBAN format · MC

Monaco IBAN format: 27 characters.

Monaco IBANs have 27 characters: the country code MC, two check digits and a 23-character BBAN, the national account number, laid out as 5!n5!n11!c2!n.

Monaco IBAN structure

MC5811222000010123456789030

Country code: MC
Check digits: 58
Bank code: 11222
Branch code: 00001
Account: 01234567890
RIB key (national check): 30

Parts of a Monaco IBAN and their positions
Positions	Part	In the example
1–2	Country code	MC
3–4	Check digits	58
5–9	Bank code	11222
10–14	Branch code	00001
15–25	Account	01234567890
26–27	RIB key (national check)	30

The BBAN, segment by segment

The registry writes the BBAN in SWIFT notation: n is a digit, a an upper-case letter, c a letter or digit, and the ! means a fixed length. 5!n5!n11!c2!n reads:

The Monaco BBAN format, segment by segment
Positions	Notation	Holds	Example
5–9	5!n	5 digitsBank code (code banque)	11222
10–14	5!n	5 digitsBranch code (code guichet)	00001
15–25	11!c	11 letters or digitsAccount number (numéro de compte)	01234567890
26–27	2!n	2 digitsRIB key (clé RIB), a national check	30

Monaco IBAN example

MC58 1122 2000 0101 2345 6789 030 is the sample the SWIFT IBAN Registry publishes for Monaco: a well-formed IBAN for showing the format, not a real account. Written electronically it has no spaces (MC5811222000010123456789030); on paper it is printed in groups of four.

Its check digits, worked through with ISO 7064 mod 97-10:

Move the country code and check digits to the end
11222000010123456789030MC58
Replace each letter with two digits (A = 10 … Z = 35)
M = 22, C = 12
11222000010123456789030221258
Divide that number by 97 and keep the remainder
Remainder 1. A valid IBAN always leaves 1, so the check digits are right.
Where the check digits come from
Put 00 in their place (MC00…), repeat steps 1–3: remainder 40. The check digits are 98 − 40 = 58.

SEPA

Monaco is in the Single Euro Payments Area, so SEPA credit transfers and direct debits can reach MC IBANs; whether a given bank takes part is up to that bank.

What the format can and can’t tell you

Valid means the structure and check digits are right — not that the account exists or can receive payments.
National check digits inside the BBAN (e.g. the French RIB key, or the Spanish, Belgian and Italian CIN digits) are not verified.
Bank and branch codes are read from their positions; they are not looked up in a bank directory.

Check MC IBANs from code or an AI agent

REST · GET · no key

curl -s 'https://payopskit.com/api/v1/iban/MC5811222000010123456789030'

MCP · tools/call · validate_iban

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "validate_iban",
    "arguments": {
      "iban": "MC5811222000010123456789030"
    }
  }
}

Response (JSON)

{
  "input": "MC5811222000010123456789030",
  "iban": "MC5811222000010123456789030",
  "print": "MC58 1122 2000 0101 2345 6789 030",
  "valid": true,
  "country": {
    "code": "MC",
    "name": "Monaco",
    "sepa": true,
    "sepaNote": null
  },
  "checkDigits": "58",
  "expectedCheckDigits": "58",
  "length": {
    "actual": 27,
    "expected": 27
  },
  "bban": "11222000010123456789030",
  "bbanFormat": "5!n5!n11!c2!n",
  "bankCode": "11222",
  "branchCode": "00001",
  "parts": [
    {
      "label": "Country code",
      "value": "MC",
      "start": 0,
      "end": 2,
      "kind": "country"
    },
    {
      "label": "Check digits",
      "value": "58",
      "start": 2,
      "end": 4,
      "kind": "check"
    },
    {
      "label": "Bank code",
      "value": "11222",
      "start": 4,
      "end": 9,
      "kind": "bank"
    },
    {
      "label": "Branch code",
      "value": "00001",
      "start": 9,
      "end": 14,
      "kind": "branch"
    },
    {
      "label": "Account",
      "value": "01234567890",
      "start": 14,
      "end": 25,
      "kind": "account"
    },
    {
      "label": "RIB key (national check)",
      "value": "30",
      "start": 25,
      "end": 27,
      "kind": "national-check"
    }
  ],
  "checks": {
    "characters": true,
    "country": true,
    "length": true,
    "bbanFormat": true,
    "checksum": true
  },
  "errors": [],
  "notes": [
    "Valid means the structure and check digits are right — not that the account exists or can receive payments.",
    "National check digits inside the BBAN (e.g. the French RIB key, or the Spanish, Belgian and Italian CIN digits) are not verified."
  ]
}

The MCP server is at /mcp (Streamable HTTP, no key); the API and MCP docs show how to connect Claude, Cursor or VS Code.

From a national account number: GET /api/v1/iban/check-digits?country=MC&bban=… or the MCP tool compute_iban_check_digits computes the check digits and the whole IBAN.

Other 27-character IBANs

The same length doesn’t mean the same structure: compare the BBAN formats. All IBAN formats and lengths

Source: the SWIFT IBAN Registry (ISO 13616), transcribed and checked against each country’s registry example; the positions of bank and branch codes are given only where the registry’s are well established. The SWIFT IBAN Registry is the authority. Informational only.