What is an IBAN number?

An IBAN — International Bank Account Number — is a standard way of writing your bank account details so that banks in other countries can identify your account exactly. It is used for international payments, and in much of Europe for domestic ones too.

The part most explanations leave out: an IBAN is not a new number you have to apply for. For a UK account it is your existing sort code and account number, with a country code and two check digits added and the whole thing rearranged into a single string. You already have one, whether or not you have ever looked it up.

Before IBANs, every country wrote account details its own way. The UK used a six-digit sort code and an eight-digit account number, Germany used a Bankleitzahl and a Kontonummer, and a bank in one country receiving instructions from another had to work out which was which. Payments went astray, and tracing them took weeks.

The IBAN solves that by putting everything into one string with a fixed structure: the country, a checksum, and the domestic account details the country already used. Any bank anywhere can read it, and — more usefully — can tell whether it has been typed correctly before the payment is sent.

That checking is the part that matters day to day. The two digits after the country code are calculated from everything else in the IBAN. Mistype a single character and the calculation fails, and the payment is rejected immediately rather than going to the wrong account.

A UK IBAN is 22 characters and begins with GB. Written out with spaces for readability, it looks like this:

GB29 NWBK 6016 1331 9268 19

The spaces are for humans. When you enter it into a payment form, type it as one unbroken string.

• GB — the country code, two letters

• 29 — the check digits, calculated from the rest of the IBAN

• NWBK — the bank identifier, four letters

• 601613 — the sort code, six digits

• 31926819 — the account number, eight digits

Your sort code and account number are visible inside it, in order. That is why you give a sender your IBAN or your sort code and account number, not both — the second is contained in the first.

The first four characters are the same everywhere: two letters for the country, two digits for the checksum. Everything after that is whatever the country already used for domestic account numbering, so the length varies with local convention.

Norwegian IBANs are 15 characters. UK and Irish IBANs are 22. German are 22, French 27, Maltese 31. The longest in use run to 33. None of this affects how you use them — a longer IBAN is not a different kind of account, just a country with longer account numbers.

It is usually already in front of you.

In your banking app, under account details or account information — often behind a heading like "international payments" or "share account details". In online banking, on the account summary or a downloadable statement. On a paper statement, generally near your sort code and account number. And if none of those work, your bank will tell you.

Because a UK IBAN is derived from your sort code and account number, it can also be calculated from details you already have. That is what IBAN checkers and calculators do. It is a reasonable way to confirm an IBAN someone has given you, though for your own account the number in your banking app is the one to trust.

Once you have it, you will want to know what else a sender needs alongside it —

No, but your account number is inside it.

Your account number identifies your account within your bank. Your IBAN identifies your account anywhere in the world, by wrapping that account number together with your sort code, your bank's identifier, your country and a checksum.

So they are not interchangeable. A sender abroad given only your eight-digit account number cannot route a payment to you; a sender in the UK given your IBAN generally can, because the form will accept it. When in doubt, give the IBAN — it contains everything the shorter details do.

No. An IBAN identifies an account. A BIC — also called a SWIFT code — identifies the bank. International payments often need both: the BIC to route the payment to the right institution, the IBAN to credit the right account inside it.

The two are covered properly in BIC and SWIFT codes explained.

Around eighty countries use IBANs, covering the whole of Europe including the United Kingdom, much of the Middle East, and parts of North Africa, the Caribbean and Central Asia. Within the SEPA area an IBAN is all that is needed for a euro payment.

Several major economies do not use them at all. The United States, Canada, Australia, New Zealand, Japan, China and most of South America use their own systems — routing numbers in the US, BSB codes in Australia, transit numbers in Canada — and send international payments by SWIFT instead. If you are being paid from one of those countries, the sender will use your IBAN and your bank's SWIFT code together.

The UK is worth noting on its own. It left the EU but remains a full SEPA participant, so a UK-issued IBAN still works for euro payments across the SEPA area on the same terms as before. Keytom issues personal [EUR IBANs in the United Kingdom], registered in the account holder's own name.

How do I find my IBAN number?

In your banking app under account or international payment details, in online banking, or on a statement. Your bank can also give it to you. For a UK account it can be derived from your sort code and account number, which is how IBAN calculators work.

Is an IBAN the same as a sort code and account number?

Not the same, but it contains them. A UK IBAN is your sort code and account number plus a country code, check digits and a bank identifier, written as one string.

What is an example of an IBAN number?

A UK IBAN looks like GB29 NWBK 6016 1331 9268 19 — 22 characters, starting with the country code GB. Other countries use different lengths, from 15 characters in Norway to 31 in Malta.

Do I need an IBAN for a payment within the UK?

No. A UK-to-UK transfer uses your sort code and account number. The IBAN is for payments arriving from outside the UK.

Can I have more than one IBAN?

Yes. Each account has its own IBAN, so if you hold accounts in more than one currency or with more than one provider you will have several. A multi-currency account gives you account details for each currency it holds.

What happens if someone sends money to the wrong IBAN?

Most mistyped IBANs fail the check digit test and are rejected before the payment leaves. If an IBAN is valid but belongs to someone else, the money does arrive there, and recovering it means asking your bank to contact the receiving bank — which depends on the recipient agreeing to return it. Check the IBAN before sending rather than after.