What is an IBAN?

An IBAN is an International Bank Account Number: a country code, a check digit, and a domestic account identifier packed into one string. SEPA and many cross-border payments use it. It is an address. It is not a balance. The ledger still needs a wallet for the person who owns that address.

How does an IBAN work?

You validate the check digits, store the string, and pass it to the rail. The bank uses it to find the account. A wrong IBAN fails at the bank, not in your ledger. A right IBAN to the wrong person is a successful payment you will struggle to reverse.

IBAN vs sort code and account number

The UK still quotes sort code plus account number for some domestic sends. An IBAN can wrap those. Store what the rail asks for. Do not invent an IBAN from a US routing number.

Where does it live?

On the payout instrument, not on the wallet id. Many wallets can share no IBAN. One identity can have several. Copy the IBAN onto the transaction metadata when you send, so the file and the book match.

How it works with Blnk

Keep the IBAN on the identity or payout method. When you originate, put it in metadata. The source and destination are still balances, not account numbers.