What is a BSB Number? Complete Guide to Australian Bank Codes

What is a BSB Number?

A BSB number, short for Bank-State-Branch number, is a six-digit numerical code used to identify individual branches of financial institutions within Australia. Every bank branch in the country is assigned a unique BSB number, which plays a critical role in routing electronic funds transfers, direct debits, and other payment transactions to the correct destination.

Think of a BSB number as a postal code for your bank branch. Just as a postal code ensures your mail reaches the right suburb, a BSB number ensures your money reaches the right bank and branch. Without it, the Australian payments system would have no reliable way to route funds between the thousands of bank branches operating across the country.

BSB numbers are used exclusively within Australia. They are not recognised by international banking systems, which rely on SWIFT/BIC codes for cross-border transactions. If you are sending or receiving money domestically within Australia, you will almost certainly need a BSB number alongside the recipient's account number.

The History of BSB Numbers

The BSB system was introduced in the 1960s as part of Australia's efforts to modernise and automate its banking infrastructure. Before BSB numbers existed, bank transactions were processed manually, with clerks sorting cheques and payment instructions by hand based on the name of the bank and branch. This process was slow, error-prone, and unable to keep pace with the growing volume of transactions.

As electronic data processing became more feasible, the Australian banking industry recognised the need for a standardised numerical coding system. The BSB number was developed to provide a machine-readable identifier for every bank branch, enabling automated sorting and routing of payments.

The system was initially managed by the Australian Payments Clearing Association (APCA), which was established in 1992 to oversee Australia's payments infrastructure. Today, the official BSB directory is maintained by the industry body responsible for managing the BSB numbering system, which processes applications for new BSB numbers and manages changes such as branch closures and bank mergers.

Over the decades, the BSB system has evolved alongside Australia's payments landscape. While the country has moved towards more centralised and digital banking -- with many physical branches closing -- BSB numbers remain a foundational element of the domestic payments infrastructure. Even institutions that operate entirely online are assigned BSB numbers for payment routing purposes.

How BSB Numbers Are Formatted

A BSB number consists of six digits, conventionally written in the format XXX-YYY with a hyphen separating the first three digits from the last three. Each segment of the number carries specific meaning:

The First Two or Three Digits: Institution Code

The leading digits of a BSB number identify the financial institution. Major banks are assigned specific numeric ranges. For example:

01x: Australia and New Zealand Banking Group (ANZ)
03x: Westpac Banking Corporation (WBC)
06x: Commonwealth Bank of Australia (CBA)
08x: National Australia Bank (NAB)

Smaller banks, credit unions, and building societies are assigned codes within other ranges. Some institutions share prefix ranges due to historical mergers and acquisitions.

The State Digit

For many of the major banks, one digit within the first three indicates the state or territory where the branch is located. The state codes generally follow this convention:

2: New South Wales (NSW)
3: Victoria (VIC)
4: Queensland (QLD)
5: South Australia (SA)
6: Western Australia (WA)
7: Tasmania (TAS)

However, this state-coding convention is not universally applied across all institutions. Some banks, particularly smaller ones and those that joined the system later, do not follow this pattern.

The Last Three Digits: Branch Identifier

The final three digits identify the specific branch within the bank and state. These are assigned sequentially or according to the institution's own internal conventions. For example, a bank's head office in a given state might be assigned 000 or 001 as the branch code.

Example Breakdown

Consider the BSB number 062-000:

06: Commonwealth Bank of Australia
2: New South Wales
000: Head office or primary branch

Another example, 033-456:

03: Westpac Banking Corporation
3: Victoria
456: A specific branch in Victoria

Who Manages BSB Numbers?

The official custodian of the BSB numbering system is the self-regulatory body for the Australian payments industry. Its responsibilities include:

Maintaining the master BSB directory, which lists every active BSB number and the institution and branch it corresponds to
Processing applications from financial institutions for new BSB numbers
Managing BSB changes resulting from branch closures, relocations, and institutional mergers
Publishing updates to the BSB directory on a regular cycle, typically every few months

Financial institutions that want to participate in Australia's direct entry (DE) system must register their BSB numbers with the industry body. The Bulk Electronic Clearing System (BECS), which processes the majority of domestic electronic payments in Australia, relies on BSB numbers to route transactions.

It is worth noting that BSB numbers are not secret or sensitive information. They identify branches, not individual customers. Your BSB number is safe to share when providing payment details to someone who needs to transfer funds to your account.

Why BSB Numbers Exist

BSB numbers serve several important purposes within the Australian financial system:

Routing Payments Accurately

The primary function of a BSB number is to route electronic funds transfers to the correct financial institution and branch. When you initiate a bank transfer, your bank uses the recipient's BSB number to determine where the funds should be sent. Without this routing information, the payment system would have no way to identify the destination.

Enabling Automated Processing

Before BSB numbers, payment processing required significant manual intervention. The standardised six-digit format allows computers to instantly identify the target institution and branch, enabling high-volume automated processing. Australia's payments system handles hundreds of millions of transactions each year, and BSB numbers make this scale possible.

Supporting Direct Debits and Credits

BSB numbers are essential for setting up recurring payments such as direct debits for bills, salary payments via direct credit, and government benefit payments. Employers, billers, and government agencies all use BSB numbers in combination with account numbers to process these automated payments.

Maintaining System Integrity

By requiring every branch to have a unique identifier registered with a central authority, the BSB system helps maintain the integrity and reliability of Australia's payments infrastructure. It provides a clear, auditable mapping between codes and physical or virtual banking entities.

How BSB Numbers Are Used in Transfers

When you transfer money to another person or business within Australia, you typically need two pieces of information:

The recipient's BSB number -- identifies their bank and branch
The recipient's account number -- identifies their specific account within that branch

Here is how a typical domestic transfer works:

You log into your online banking or visit your branch and initiate a transfer.
You enter the recipient's BSB number and account number, along with the amount and any reference or description.
Your bank reads the BSB number and determines which financial institution and branch the payment should be routed to.
The payment is submitted to the Bulk Electronic Clearing System (BECS) or the New Payments Platform (NPP), depending on the type of transfer.
The receiving bank processes the incoming payment and credits the recipient's account.

For standard BECS transfers, this process can take one to two business days. For NPP (Osko/PayID) transfers, funds can arrive within seconds, though BSB numbers are still used in the underlying routing infrastructure.

BSB Numbers and Online-Only Banks

With the rise of digital banking in Australia, several financial institutions now operate without physical branches. Banks such as ING, UP, and 86 400 (now part of NAB) conduct all their business online or through mobile apps. Despite having no physical branches, these institutions are still assigned BSB numbers.

In most cases, an online-only bank will have a single BSB number that applies to all of its customers, rather than a range of BSB numbers across different states and suburbs. For example, ING Australia uses the BSB 923-100 for its savings and transaction accounts. This number routes all payments to ING's centralised processing system.

The existence of BSB numbers for branchless banks demonstrates that the code has evolved beyond its original purpose of identifying physical branches. Today, it functions more broadly as a routing identifier for financial institutions within Australia's payments network.

Common Questions About BSB Numbers

Is my BSB number the same as my account number?

No. Your BSB number identifies your bank and branch, while your account number identifies your specific account. You need both to receive a domestic transfer.

Can I have different BSB numbers for different accounts?

Yes. If you hold accounts at different branches of the same bank, each account may have a different BSB number corresponding to the branch where it was opened. However, with modern banking, many customers are assigned a single BSB regardless of which branch they visit.

Yes. A BSB number identifies a bank branch, not an individual. Sharing your BSB and account number is necessary for receiving payments and does not give anyone the ability to withdraw funds from your account.

Do BSB numbers ever change?

BSB numbers can change, most commonly when banks merge, branches close, or institutions restructure. When a BSB number changes, the bank typically provides a transition period and notifies affected customers. During the transition, payments sent to the old BSB are automatically redirected to the new one.

Looking Up a BSB Number

If you need to find or verify a BSB number, BSBFinder provides a free, easy-to-use lookup tool. Simply enter a BSB number to find the associated bank and branch, or search by bank name and location to find the BSB you need. Keeping your BSB details accurate and up to date is important for ensuring your payments are routed correctly and without delay.