Australian Tax File Number (TFN) Generator & Validator

Frequently asked questions

What is an Australian Tax File Number (TFN)?

A TFN is a unique 8 or 9-digit number issued by the Australian Taxation Office (ATO) to individuals, companies, superannuation funds, partnerships, and trusts. It is used to identify taxpayers in Australia's tax and superannuation systems. Individuals use their TFN when starting employment, opening a bank account, or lodging a tax return.

Why is there no TFN generator?

TFNs are highly sensitive personal identifiers. Unlike ABNs and ACNs, which identify businesses and companies, TFNs identify individual taxpayers. Generating fake TFNs creates unacceptable risk of misuse for tax fraud, identity theft, and payroll evasion. This tool validates format and check digit only — no TFNs are generated.

How does TFN validation work?

For a 9-digit TFN, multiply each digit by the weights [1, 4, 3, 7, 5, 8, 6, 9, 10] and sum the products. A valid TFN produces a sum that is exactly divisible by 11. For 8-digit TFNs (older format), no publicly documented check-digit standard exists, so this tool accepts them by length alone.

What makes a TFN format valid?

A TFN must be 8 or 9 digits with no letters or special characters. For 9-digit TFNs, the weighted sum using [1,4,3,7,5,8,6,9,10] must be divisible by 11. Passing this check does not mean the TFN is registered with the ATO — it only means the number is structurally correct.

Is it safe to paste a TFN into this tool?

Yes. The TFN is validated entirely in your browser — it is never sent to any server, logged, or stored. The algorithm runs in client-side JavaScript. That said, as a matter of good practice, avoid pasting real TFNs into any website unless you have verified its privacy and security practices.

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