What is a Tax File Number (TFN)?

Understand what a TFN is, why it matters, and how it is used for tax and superannuation.

Summary

A tax file number (TFN) is a personal reference number issued by the ATO for tax and superannuation purposes. It is free to apply. While you are not legally required to have a TFN, having one helps you manage your tax and can prevent higher amounts of tax being withheld from some payments.

What this means

Your TFN identifies you to the ATO. It is used across tax, super and some government services. You only need to apply once — a TFN stays with you for life, regardless of name or address changes.

You are not legally required to have a TFN, but without one, tax may be withheld from your pay at the highest rate and you may not be able to claim the tax-free threshold. Your TFN is sensitive personal information and should be kept safe.

Typical actions

  • Check if you already have a TFN by looking at past ATO letters or income statements.
  • If you do not have one, apply through the ATO or Services Australia.
  • Provide your TFN to your employer, bank or super fund when appropriate.
  • Keep your TFN private and secure, like other personal identity information.
  • Report to the ATO promptly if your TFN is lost, stolen or misused.

Official ATO sources

Last checked: 24 August 2026

Tax file number
Main ATO hub about applying for, finding and protecting your TFN.

Australian residents – TFN application
Explains how Australian residents can apply for a TFN.

Lost or stolen TFN
What to do if your TFN is lost, stolen or misused.

Related questions

Important notice: Tax Clarity is an independent information tool. This page provides general information based on official sources. It does not provide tax, legal, financial, or accounting advice. Tax rules can change, and how they apply depends on your circumstances. For advice about your situation, speak with a registered tax agent or qualified professional.

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