Belgian bank code check — the NBB list

Belgian bank codes are short: three digits, positions 5–7 of a BE IBAN. Which makes Belgium the one country where the whole allocation table fits on a screen — and the National Bank of Belgium publishes exactly that: all 1,000 slots in a single public file (full_list_current.xlsx), served here as the register Banque nationale de Belgique, bank identification codes (Protocol Secretariat).

A three-digit code space with a published state for every slot means the negative answer is unusually solid. There is no "we haven't seen it" in Belgium. Every code is either allocated to a named institution or explicitly not.

One call

curl -X POST https://api.ibanforge.com/v1/iban/validate \
  -H "Content-Type: application/json" \
  -d '{"iban": "BE68539007547034"}'

{
  "valid": true,
  "bank_code_check": {
    "value": "539",
    "status": "not_in_register",
    "match": null,
    "register": "Banque nationale de Belgique, bank identification codes (Protocol Secretariat)",
    "authoritative": true,
    "as_of": "2026-08"
  }
}

BE68 5390 0754 7034 is the most-copied example IBAN in the world — European standards material, a thousand tutorials, countless test fixtures. Its bank code 539 is one of the eight slots the NBB itself marks "Onbeschikbaar / Indisponible": reserved, allocated to nobody. valid: true and not_in_register are both correct, and the gap between them is the entire reason to check bank codes at all. The full story, with the Swiss and Austrian equivalents, is in the world's two favourite example IBANs point at bank codes that don't exist.

The arithmetic of 1,000 slots

In the NBB file dated 5 August 2026, the numbers close exactly:

State in the file	Slots	How we treat it
Allocated to a named institution	781	`verified`
`VRIJ` (vacant)	211	unallocated
`Onbeschikbaar` / `Indisponible` (reserved, unavailable)	8	unallocated
Total	1,000

Both non-allocated states answer not_in_register. A reserved slot is not a bank: the register writes VRIJ where an institution name would go, so a lookup that stored those rows would happily report a bank called "VRIJ" — the exact inversion of what the file says. We drop them on purpose.

What the NBB file publishes — and what it does not

Field	In the Belgian file	Note
`name`	yes	the institution's name, published in up to four languages
`street`	no	`null`
`post_code` / `town`	no	`null`
`lei`	no	the key is simply absent from the response

The Belgian file is a name-only register: no addresses, in any language. So bank_code_check.institution for Belgium carries a name and honest nulls around it. Those nulls are the shape of what Belgium publishes, not missing work on our side — filling them from a BIC directory would attribute to the NBB an address it never printed.

What `not_in_register` means here

authoritative: true marks it as the register's own verdict: within a code space where every one of the 1,000 slots has a published state, the code is not allocated to any institution. For a payment about to leave, that is a strong reason to stop and check the beneficiary details — while the IBAN's checksum keeps saying valid: true, because mod-97 only catches transcription errors.

The honest limits

We check the bank code, never the account or its holder. A verified Belgian code names the institution the three digits belong to, and stops there.
Names, not addresses. See the table above — Belgium publishes no address, so we serve none.
Monthly freshness. The list is re-read monthly; every answer carries the edition in as_of (2026-08 above), so you always know how fresh the verdict is.
A reserved slot can be activated later. Onbeschikbaar today does not mean forever — it means the NBB has not allocated it as of the edition that answered.