Insight
What Is a Tax File Number (TFN) and How Do You Find Yours?
12 Jan 2026
In short
A Tax File Number (TFN) is a nine-digit personal reference issued by the Australian Taxation Office to individuals and entities for tax and superannuation purposes. It is not compulsory, but without one, wages are taxed at the top marginal rate, interest is taxed at 47%, and you cannot lodge online.
What a TFN is
A Tax File Number (TFN) is a nine-digit number issued by the Australian Taxation Office (ATO) to individuals, companies, trusts, partnerships and superannuation funds. It is the primary identifier the ATO uses to track tax and superannuation obligations.
A TFN is not compulsory — but without one, employers, banks and super funds must withhold tax at the top marginal rate. In practice, everyone earning income in Australia needs one.
How to apply for a TFN
- Australian citizens apply through the ATO website using myGovID.
- Foreign passport holders and permanent migrants apply online after arriving in Australia.
- Businesses (companies, trusts, partnerships) apply for a TFN as part of the ABN registration process on the Australian Business Register.
How to find a lost TFN
You can find your TFN on any income tax notice of assessment, your PAYG payment summaries, super fund statements, or by logging into myGov and linking the ATO service. You can also phone the ATO and answer identity-verification questions.
Business obligations when collecting TFNs
Employers, super funds and financial institutions can collect TFNs for authorised purposes but must handle them under the Privacy (Tax File Number) Rule 2015. That rule imposes strict use, disclosure and security obligations, and misuse can trigger both privacy and tax penalties.
If your business handles TFNs, your privacy policy, staff training and data-retention practices need to reflect those obligations. Envision Legal can review your handling practices as part of a broader privacy compliance check.
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