What is an IBAN number UK banks issue, and what does it contain?

Finding yours

1. Open your banking app. Starling tells its customers exactly where to look: "Starling customers can see their IBANs in the app by selecting the top right-hand menu, then 'Account details' and then 'International'." Most UK apps hide the IBAN one level below the domestic details for the same reason: almost nobody needs it domestically.
2. Check a statement. Nationwide: "You can find your IBAN on your monthly account statement. Or you can use the app and internet bank." A statement is a good fallback when you have lost access to the app.
3. Use the bank's generator, not a third party's. Barclays offers a tool "to generate your IBAN for any of your Barclays accounts". Use the bank's own, because the four-letter bank code inside an IBAN differs between brands that share a banking licence, and a third-party generator that guesses it produces a number that passes the check digits and still fails.
4. Ask, if none of that works. Starling's general advice covers the rest: "You can also get in touch with your bank and ask." It is the only route that is certain for an account you no longer have digital access to.

The 22 characters, block by block

GB, then two check digits, then four letters for the bank, then the six-digit sort code, then the eight-digit account number. Monzo's breakdown names the last two blocks in the customer's own vocabulary: "123456 – sort code: the next six numbers are your standard domestic sort code" and "12345678 – account number: the final eight numbers are your standard domestic bank account number". Once you have seen that, a UK IBAN stops looking like a random string and starts looking like your own details with a header.

What the check digits are for

The Co-operative Bank describes the second block as a "check number" that "helps a banking institution to validate an IBAN". The arithmetic behind it is the ISO 13616 modulo-97 rule, and its practical effect is that a single mistyped character almost always fails at the sending bank rather than arriving somewhere unexpected. It is a typo catcher, not a guarantee that the account exists or that the name on it is the one you were given.

When a UK IBAN is required, and when it is theatre

An IBAN is mandatory for payments within the European Economic Area and is commonly requested for any payment crossing a currency. It is not used for domestic UK payments at all, and the United States has no IBAN system, so a US supplier can accept yours and cannot give you theirs. If a UK business asks you for an IBAN for a payment in pounds between two UK accounts, they have asked for the wrong thing; your sort code and account number are what that payment needs.

Questions people ask

Is IBAN number tautological?

Slightly, yes. Monzo points out that the phrase is "technically incorrect" because the N in IBAN already stands for number. Everyone searches for it that way, so the phrase is used here too.

How long is a UK IBAN?

22 characters. Other countries differ, which is why an IBAN from abroad may be shorter or longer without being wrong.

Does my IBAN change if I move branch?

It changes if your sort code or account number changes, because both sit inside it. A brand change that keeps your account numbers intact leaves the IBAN's last fourteen characters alone but may change the four-letter bank code, so regenerate it from the app after any migration.

The same question in the other market

• Sort code checker across the index
• SWIFT code across the index
• Bank identification code across the index
• Account number across the index
• IBAN number UK across the index