The encyclopedia · Finance & Accounting · Technical decision · 1997–2026
IBAN built check digits into account numbers so transfers self-verify
An IBAN adds a country code and two check digits, so a mistyped account is caught before the payment leaves.
SWIFT · ISO
the move
Sending money across borders meant typing an account number that another country's bank might read differently, and a single typo sent funds to the wrong place or bounced.
ISO 13616 standardized the IBAN: a country code, two check digits and the domestic account number. SWIFT is the registration authority for each national format, so length and layout are agreed in advance.
The genius is the check digits. The number passes a mod-97 calculation, so both the sending and receiving bank can prove the account is legitimate before any money moves; errors are caught instantly.
why it works
- Check digits make the number self-validating, so typos fail at entry.
- A standard country code plus an agreed structure removes cross-border ambiguity.
- A registration authority keeps every national format published and consistent.
what transfers
When errors are costly and hard to undo, move validation into the identifier itself so the failure is caught at entry, not in settlement.
what came after
IBAN became mandatory across the Single Euro Payments Area and then globally, drastically cutting rejected and misrouted payments. It quietly removed a whole class of transfer errors and paved the way for SEPA instant payments that move in seconds.
references
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