Australian Tax File Number (TFN) Generator & Validator
Generate and validate Australian Tax File Numbers (TFN) for software testing and development only. The weighted check-digit algorithm runs entirely in your browser.
For testing and development only. Generated TFNs are mathematically valid but not registered with the Australian Taxation Office. Do not use them to lodge tax returns, misrepresent identity, or for any purpose other than software testing and development.
Australian Tax File Number
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No additional info
Sample Australian TFNs
How to use it
- 1Enter or paste a TFN (8 or 9 digits, spaces are ignored) into the input field.
- 2Click Validate to check whether the number passes the official format and check-digit rules.
- 3The result shows each check that was applied and clearly flags which one failed, if any.
- 4Use the example TFN 123 456 782 to verify your understanding of the algorithm — it is the widely documented test number.
Common use cases
- Validate TFNs entered in a payroll or HR onboarding form before sending them to a backend service.
- Check whether a TFN passes the ATO's format rules as a first line of defence before a full ATO validation call.
- Demonstrate the TFN check-digit algorithm to developers building Australian payroll or tax software.
- Audit your own TFN validation implementation by comparing its output against this tool.
- Confirm that a TFN in a test fixture is structurally valid before running automated payroll tests.
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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