Finland formats its IBAN in 18 characters with the BBAN pattern ^[0-9]{14}$: an all-numeric domestic account number, carried over unchanged from the pre-IBAN Finnish account number.
Breakdown
The official registry example is FI21 1234 5600 0007 85, a SWIFT registry test value rather than a real account:
FI21- country code and IBAN check digits123- the bank identifier the tool highlights: the leading digits that identify the bank or banking group (the 1-block is Nordea)45600000785- the rest of the domestic account number, ending in a national check digit
The bank-code system
Finnish institution codes (rahalaitostunnus) are coordinated and published by Finanssiala (Finance Finland), the sector’s trade body, which maps each to a bank name and BIC. Unusually, the codes are variable length, set by the leading digit: a single digit for the large groups (1 and 2 are Nordea, 5 is OP, 6 is the Bank of Åland, 8 is Danske Bank), two digits for the 3-prefixed banks (31 Handelsbanken, 33 SEB, 38 Swedbank), and three digits for the 4-, 71- and 79-prefixed institutions (405 and 497 Aktia, 470-479 the POP banks, 715 the savings banks); since 2024 the 72-78 range is issued as four-digit codes. Because a one-digit code owns an entire leading-digit block, a handful of leading digits fan out across the three-digit prefixes an IBAN can begin with, all resolving to about twenty institutions. There is no separate branch field.
Currency and SEPA context
Finland is a European Union member and, unlike its Nordic neighbours, uses the euro - it joined the eurozone at the outset. It participates fully in the SEPA schemes, so euro transfers to and from FI IBANs run on standard SEPA rails as domestic-equivalent payments.
Validity remains structural only. An 18-character string that passes the MOD-97 check digits may reference a closed account or an unissued institution code, and it says nothing about the holder’s identity. Finland’s domestic account number carries its own check digit, but it is not validated by the IBAN checksum. Name-matching services in the style of the EU’s Verification of Payee are the safeguard against paying a well-formed number that belongs to the wrong person.