Australia ABN number guide
Australian Business Number(ABN)
Australian enterprises utilize the Australian Business Number (ABN) as a unified identifier for all interactions with the Australian Taxation Office (ATO) and for engagements with other governmental departments and agencies. The ABN is also a key component for tax identification purposes. To enroll for the goods and services tax and other facets of The New Tax System (Goods and Services Tax) Act 1999, businesses are required to obtain an ABN. Much like the Tax File Number (TFN), the application process for an ABN can be carried out online or through traditional paper channels. Furthermore, the registration for the goods and services tax can be concurrently completed with the ABN application. The introduction of the ABN by the Australian Government was in response to the recommendations of the Small Business Deregulation Task Force Report, aiming to provide a singular identifier to streamline business interactions with the Australian Government.A client’s ABN is available to State, Territory and local government regulatory bodies to streamline registration requirements.
Format
The ABN is a unique 11 digit number formed from a nine digit unique identifier and two prefix check digits. The two leading digits (the check digits) will be derived from the subsequent nine digits using a modulus 89 check digit calculation. The check digits will be included to identify common data entry errors such as digit transposition. The ABN will be structured as XX XXX XXX XXX.
For bodies registered under Corporations Law, their ABN will be formed by prefixing two digits to their Australian Company Number or Australian Registered Business Number issued by the Australian Securities and Investment Commission (ASIC). These companies must have their identity established and first register with ASIC prior to the normal registration process for an ABN. The ABN will eventually replace the ACN and the ARBN
ABN search is freely available for public us on ABN lookup tool
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| Australian Business Number |
Australian Tax File Number (TFN)
In Australia, the Tax File Number (TFN) serves as the Tax Identification Number. It is utilized by both individuals and entities involved in interactions with the Australian Taxation Office (ATO). These interactions encompass reporting information to the ATO, filing income tax returns, and engaging in the superannuation (retirement income) system. A TFN can be allocated to individuals as well as non-individual entities such as companies, trusts, partnerships, and superannuation funds.
The issuance of a TFN is governed by the Income Tax Assessment Act 1936 (ITAA 1936) and occurs upon application by the client or as deemed necessary by the ATO for internal purposes. The application process for a TFN is flexible, allowing applicants to apply online or through traditional paper channels. The TFN is issued upon satisfactory submission of proof of identity, which, for individuals, includes one primary document (birth certificate, passport, citizenship certificate) and up to two secondary documents (driver's license, Medicare card, bank statement, firearms license, student card, proof of age card, student examination certificate). Proof of identity requirements for partnerships, companies, and trusts involve establishing the identity of the partners, director(s), public officer, and trustee, respectively.
Format
The TFN is an eight or nine digit number compiled using a check digit algorithm to allow accurate data capture of the TFN in ATO systems. Generally the TFN is displayed on correspondence as three sets of three numbers (for example XXX XXX XXX) but is stored as an eight or nine number string on internal systems.
Frequently Asked Questions
My contractor invoice was short-paid — why did my client hold back 47%?
This is the PAYG no-ABN withholding rule. If you supply goods or services worth more than A$75 (excluding GST) and do not quote an ABN on the invoice, your client is legally required to withhold 47% of the gross payment and remit it to the ATO. This has been the applicable rate since 1 July 2017, matching the top marginal income tax rate. The withheld amount is not lost — the supplier can claim it back as a tax credit in their income tax return. To avoid withholding, quote your ABN on every invoice. If a legitimate exception applies (e.g., the supply is a private hobby activity), the supplier can provide a completed "Statement by a supplier" form instead. [1] [2]
The ATO cancelled my ABN without warning — what happens now and can I reactivate it?
The Australian Business Register runs an ongoing integrity program that identifies ABNs where there are no signs of business activity — no income reported in tax returns, no BAS lodgements, no third-party evidence of trading. When selected, the ABR may contact you to provide proof of enterprise, but cancellations can proceed with limited notice. A cancelled ABN means clients must withhold 47% from your invoices, and you may lose GST registration and any business name linked to the ABN. To reactivate, apply at abr.business.gov.au — your original ABN can be restored if entitlement is re-established. If you are still trading but never received the notice, check the "Historical details" tab on ABN Lookup, which records the exact cancellation date so you can identify which invoices were affected. [3] [4]
I'm on a working holiday visa — will my employer withhold tax correctly without my TFN?
Without a TFN, your employer must withhold tax at the maximum rate of 45% from every payment, regardless of how little you earn. Providing your TFN allows employers registered with the ATO as "working holiday maker employers" to apply the concessional flat rate of 15% on the first A$45,000 of income in the year (rates above that threshold follow a separate schedule). If your employer is not registered, they must withhold at foreign resident rates (32.5% up to A$135,000) even when you have a TFN. Apply for a TFN via the ATO website or Australia Post before starting work; processing takes up to 28 days. Overpaid withholding is recoverable through a tax return at year end, but a refund does not undo the cash-flow impact during the year. [5] [6]
Does having an ABN automatically register my business for GST?
No — ABN registration and GST registration are entirely separate steps. An ABN is required for virtually all business activity; GST registration is only compulsory once your GST turnover reaches A$75,000 in a 12-month period (A$150,000 for non-profit organisations). Many sole traders and freelancers on Whirlpool and ATO Community forums discover this too late: they hold an ABN, hit the threshold mid-year, and face a back-dated GST liability on invoices that never included GST. You must register within 21 days of becoming aware that your turnover will exceed the threshold. Once registered, you must issue tax invoices and lodge BAS returns quarterly (or monthly if elected). Voluntary registration is available below the threshold and may benefit businesses with significant input tax credits. [7] [8]
As an overseas business selling digital products to Australians, do I need an ABN and GST registration?
You do not need an ABN, but you do need GST registration once your GST turnover from Australian consumers reaches A$75,000 in any 12-month period. This covers imported digital services (SaaS, streaming, e-books, online courses) and low-value physical goods under A$1,000. Non-resident businesses with no Australian presence use simplified GST registration — a lighter reporting regime accessed via an AUSid account on the ATO's non-resident online services portal. Under simplified registration you collect and remit 10% GST on B2C sales but cannot claim input tax credits; standard registration is required if you wish to claim credits. If you sell through an electronic distribution platform (marketplace), GST liability shifts to the platform operator, which may remove your own registration obligation below the threshold. [9] [10]
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