What is a tax file number in Australia?

Answer

A Tax File Number (TFN) in Australia is a unique nine-digit number issued by the Australian Taxation Office (ATO) to individuals and organisations. It is your personal reference number for the Australian tax and superannuation systems.

Australian Taxation Office (ATO)
Last Updated:May 6, 2026

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How it works in practice

What is a Tax File Number (TFN)?

A Tax File Number (TFN) is a unique nine-digit number issued by the Australian Taxation Office (ATO). It serves as a personal reference for your dealings with the ATO and other government agencies concerning tax, superannuation, and government benefits. It is a crucial identifier that helps the ATO manage your tax affairs accurately and ensures you pay the correct amount of tax.

Why is a TFN important?

Having a TFN is not compulsory, but without one, you will pay more tax. Employers are required to withhold tax at the highest marginal rate if you don't provide a TFN. It is also essential for accessing government benefits, lodging tax returns, and managing your superannuation. Financial institutions apply higher withholding tax rates to interest earned if you don't provide your TFN. Your TFN is a private and confidential number that should be protected.

Important exceptions

None identified.

What you should do now

  1. Apply for a TFN online through the ATO website if you are an Australian resident over 16, or through specific channels if you are a foreign resident or require a paper form.

  2. Provide your TFN to your employer when you start a new job to ensure you are taxed at the correct rate and avoid paying extra tax.

  3. Supply your TFN to your superannuation fund so they can accept all types of contributions and properly manage your super.

  4. Include your TFN in your annual tax return to link your income, deductions, and tax liabilities with your unique identifier.

  5. Keep your TFN confidential and only provide it to authorised entities such as the ATO, your employer, super fund, or financial institutions.

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