What is a tax file number?

A Tax File Number (TFN) is a unique nine-digit number issued by the Australian Taxation Office (ATO) to identify individuals and businesses for tax purposes. Every working Australian needs a TFN, which is used by employers, banks, and government agencies to track income, deductions, and superannuation contributions across a person's lifetime.

Applying for a TFN is free and is usually done through myGov for citizens and permanent residents who are in Australia, or through the Department of Home Affairs as part of an arrival into Australia for many visa holders. The ATO normally issues the TFN within 28 days. Once issued, the TFN is yours for life, regardless of changes in name, address, or visa status. There is no need to apply for a new TFN if you change jobs, get married, or move overseas and back.

Providing a TFN to an employer is voluntary, but without one your employer must withhold tax at the highest marginal rate (47 per cent including the Medicare levy) rather than at the standard PAYG rates. Banks and other financial institutions can also withhold tax on interest earned at the top marginal rate if no TFN is provided. Superannuation funds will not accept personal contributions without a TFN, and the Australian Taxation Office cannot match payments to a member's account without one.

TFNs must be kept confidential. The ATO advises Australians never to provide a TFN over email or to anyone who has not legally requested it. Common legitimate requests come from employers (on a TFN Declaration form when starting a new job), banks and credit unions (when opening interest-bearing accounts), Centrelink and the Department of Veterans' Affairs (for benefits and pensions), superannuation funds, the Higher Education Loan Programme (HECS-HELP), and the ATO itself. Misuse or theft of a TFN can lead to serious tax fraud, and the ATO has dedicated identity-protection support on 1800 467 033.