5F53

International Bank Account Number is the standardised, country-prefixed account identifier already familiar from ordinary banking outside EMV entirely, carried here as an optional card data element for the, comparatively rare, case where a card's underlying account needs to be identified in IBAN form rather than, or alongside, the PAN (5A, referenced alongside it, already covered in this dictionary). It's related to the Bank Identifier Code (5F54, covered alongside it here), since an IBAN and a BIC together are the pair typically needed to fully specify a bank transfer destination in markets that use the IBAN system, distinct from card-network routing that relies on the PAN and IIN (42) instead. Because IBAN carries genuine account-identifying information, though structured differently from a PAN, a terminal or system handling 5F53 should apply comparable care to how it logs, displays, or transmits it as already described for the PAN itself - it's a second form of the same category of sensitive account identifier, not a lesser one merely because it's less commonly populated. See EMV 4.4 Book 3.