Ireland’s IBAN is 22 characters, structurally the twin of the UK format: the BBAN pattern is ^[A-Z0-9]{4}[0-9]{14}$ - a 4-character bank identifier, a 6-digit sort code and an 8-digit account number.
Structure
The official registry example is IE29 AIBK 9311 5212 3456 78, a SWIFT registry test value rather than a real account:
IE29- country code and IBAN check digitsAIBK- 4-character bank code, usually the first four letters of the BIC (AIB here)931152- the 6-digit National Sort Code (NSC)12345678- the 8-digit account number
Note one subtle difference from the UK: the Irish specification allows the 4-character bank field to be alphanumeric, not strictly alphabetic, which is why the pattern reads [A-Z0-9]{4} rather than [A-Z]{4}.
Shared heritage, separate systems
Ireland and the UK ran interconnected clearing for decades, and the NSC plus account number pair is functionally identical to the British sort code system. Since Ireland adopted the euro at its launch and completed SEPA migration in 2014, domestic Irish payments quote IBANs only; the NSC survives inside the IBAN but is no longer used as a standalone identifier. There is no domestic check digit in the Irish BBAN, so the IBAN’s MOD-97 check digits are the only arithmetic safeguard.
A fintech hub’s IBANs
Ireland is a founding eurozone and SEPA member, and Dublin’s role as an EU base for international banks and e-money firms means IE IBANs appear in contexts far beyond Irish retail banking: salary accounts at fintechs, marketplace payout accounts and corporate treasury accounts all carry IE prefixes. This is legitimate, but it also means an IE IBAN alone tells you little about where an organisation actually operates.
As with any country, a validating IE IBAN is a statement about structure only. The account may not exist, and no checksum reveals the holder. Verification of Payee name matching is the EU-mandated control that closes that gap before a transfer settles.