The TFN and why to understand it before working in Australia

A TFN (Tax File Number) is a personal tax identification number issued by the ATO — nine digits, unique for life. A separate guide explains how to apply for your first TFN. This article focuses on something different: what the TFN connects to in the financial system, and why you need to understand that before you start working.

What the TFN connects to

The TFN appears at four main points in the Australian financial system:

Your employer: When you start a job, you complete a tax file number declaration to give your employer your TFN. If you do not provide a TFN, your employer must withhold tax at the highest rate set by law — you will have more deducted than necessary, though you may get it back when you lodge your end-of-year return.

Your bank account: When you open an account, the bank asks for your TFN. If you do not provide it, the bank must withhold tax from your interest at the highest rate. You are not required to provide your TFN — but not providing it usually leads to higher tax being withheld.

Your super fund: When you join a super fund, you need to give the fund your TFN. Without it, your employer’s contributions to your super may be taxed at a higher rate.

Your annual tax return: The TFN is the identifier the ATO uses to link your tax records. Without a TFN, you cannot lodge a tax return in the normal way.

The TFN does not change

Your TFN is yours for life — it does not change when you switch jobs, change your name, move to another state, or become a permanent resident. If you forget your TFN, you can find it again through your myGov account or by contacting the ATO.

The TFN is not tied to any particular visa — many visa types that allow work in Australia are eligible for a TFN. The ATO checks visa conditions when it assesses an application.

Protecting your TFN

A TFN is sensitive information. The ATO advises against sharing your TFN outside the situations where it is genuinely needed: your employer, your super fund, your bank, and your tax return.

A few points to keep in mind:

• A landlord has no legitimate reason to ask for your TFN.
• A recruiter does not need your TFN during the interview stage — only when you start work.
• If someone asks for your TFN without a clear reason, be cautious.

If you suspect your TFN is being misused, contact the ATO directly through ato.gov.au.

myGov and ATO online

myGov is Australia’s main government services portal. A myGov account linked to the ATO lets you view your tax history, your super information, and related financial details. Creating a myGov account and linking it to the ATO is a practical first step in managing your finances in Australia.

It is also where you lodge your tax return (through myTax), check your active super accounts, and receive notices from the ATO.