A BSB number is a six-digit code that identifies which branch of a bank holds your account

BSB stands for Bank Sort Code, and it tells the banking system exactly where your account lives within a bank's network. Every branch of every bank in the UK has its own BSB number. When you send money to someone or receive a payment, the BSB number routes that money to the correct physical or processing location.

You'll find your BSB number printed on the bottom left of your cheques, in your online banking portal, on statements, and on any letter your bank sends you about your account. It always comes as three pairs of digits — for example, 20-83-50. The format matters because sorting systems read it that way.

BSB numbers are used alongside your account number (usually 8 digits) to create a complete address for your money. Together, they form the routing information that banks need to move funds between accounts. Without a correct BSB number, a payment can be delayed, sent to the wrong account, or rejected entirely.

Key Takeaways

  • A BSB number is a six-digit code that identifies your bank branch; it appears on cheques, statements, and in your online banking.
  • You need your BSB number whenever you set up a payment, receive a transfer, or give banking details to an employer or organisation.
  • BSB numbers are specific to branches, so two people at the same bank may have different BSB numbers if their accounts are held at different locations.
  • Entering an incorrect BSB number can send your payment to the wrong account or cause the transaction to fail.

Where to find your BSB number

The fastest place to look is your cheque book. The BSB number is printed in the bottom left corner, before your account number and cheque number. If you don't have cheques, log into your online banking — most banks display it on the account summary page or in a section labelled "account details" or "sort code".

Your bank statement also shows the BSB number, usually near the top where your account information is listed. If you've received a letter from your bank about your account, the BSB is often printed there too. You can also call your bank's customer service line and ask them to confirm it over the phone.

Some banks print the BSB on your debit card, though not all do. If you're unsure, the safest route is to check your online banking or call your bank directly — it takes less than a minute, and you'll have the correct number.

When you need to provide your BSB number

You'll need your BSB number whenever someone needs to send money into your account. This includes setting up a direct debit or standing order, receiving a bank transfer from a friend or family member, having your salary paid in, or receiving a refund from a company. Any time you give your banking details to another person or organisation, include both your BSB number and your account number.

Employers need your BSB number to set up your payroll. Landlords need it if you're paying rent by bank transfer. Utility companies, insurance providers, and online retailers all use it to process refunds. If you're receiving money from abroad, the sender may need additional information (like an IBAN), but within the UK, the BSB and account number are the standard.

You do not need to provide your BSB number for card payments, contactless payments, or payments made through payment apps like PayPal or Revolut — only for direct bank-to-bank transfers.

What happens if you enter the wrong BSB number

If you give an incorrect BSB number, the payment may be sent to a different account at a different branch, or it may be rejected by the receiving bank's system. Modern banking systems have some protection built in: if the BSB doesn't match the account number you've provided, the bank may flag it and ask you to confirm before processing.

If money does go to the wrong account, it's not lost forever, but recovery takes time. The sending bank can trace the payment and contact the receiving bank to ask them to return it. This process usually takes 5 to 10 working days. The person or organisation who sent the money is responsible for asking their bank to retrieve it — you can't do it directly yourself.

To avoid this, always double-check the BSB number before confirming a payment. If someone has given you their details, ask them to confirm it a second time, especially if you're sending a large amount.

BSB numbers versus account numbers and IBANs

Your account number is an eight-digit code unique to your individual account. Your BSB number identifies the branch. Together, they form the complete UK banking address. You always need both for a domestic transfer.

An IBAN (International Bank Account Number) is used for payments outside the UK. It includes your BSB number and account number, plus a country code and check digits, all in one longer string. If you're sending money to or receiving money from another country, you'll use the IBAN instead of the BSB and account number separately.

Some online payment systems ask for an IBAN even for UK transfers. If you have your BSB and account number, you can construct your IBAN, or you can ask your bank to provide it directly. Most banks show your IBAN in online banking under "account details".

Why banks use BSB numbers instead of branch names

Sorting by a six-digit code is faster and more reliable than sorting by branch name. A computer can process millions of transactions per day using codes; using names would create delays and errors. The BSB system has been in place since the 1960s and is now embedded in every UK bank's infrastructure.

Each BSB number is unique and permanent for that branch. If a branch closes or merges, the BSB may be reassigned or retired, but the system itself doesn't change. This standardisation is why UK banking transfers are generally fast and reliable — the routing information is always in the same format and the same place.

Frequently Asked Questions

Can two people at the same bank have different BSB numbers?

Yes. If your accounts are held at different branches, you'll have different BSB numbers. Some people have accounts at multiple branches and each one has its own BSB. The account number is what makes your account unique within that branch.

Is my BSB number private information I should keep secret?

Your BSB number is not sensitive in the way your PIN or password is. It's safe to share it with anyone who needs to send you money. However, always give it only to people or organisations you trust, and never share it in response to an unsolicited email or phone call claiming to be from your bank.

What if my bank branch closes — does my BSB number change?

When a branch closes, your account is usually transferred to another branch and you're given a new BSB number. Your bank will notify you of the change and provide your new details. You'll need to update any standing orders or direct debits with the new BSB.

Do I need a BSB number to use online banking or mobile banking?

No. You log into online banking with your username, password, or biometric authentication. The BSB number is only needed when you're sending money out or receiving money from someone else's account.

Can I look up someone else's BSB number if I know their name and bank?

No. BSB numbers are not publicly searchable by customer name. If someone wants to send you money, they need you to provide your BSB and account number. You can't find this information about someone else without asking them directly.