A Tax File Number (TFN) is a unique identifier issued by the Australian Taxation Office (ATO) to each taxpaying entity, including individuals, companies, superannuation funds, partnerships, or trusts. It is a 9-digit number that identifies you in the tax and superannuation systems and is free to apply for. Your TFN is a personal reference number that is an important part of your identity and is yours for life, even if you change jobs, name, move interstate, or go overseas.

Not all individuals have a TFN, and a business has both a TFN and an Australian Business Number (ABN) . If a business earns income as part of carrying on its business, it may quote its ABN instead of its TFN. A TFN can be issued to individuals or non-individual entities such as companies, trusts, partnerships, and superannuation funds.

Applying for a TFN is free, and you can apply for it at any age. You will need to prove your identity by providing identity documents, and you should receive your TFN within 28 days after the ATO receives your completed application and required identity documents.

Your TFN is how the ATO identifies you in the tax and super system, and only certain individuals, organizations, or agencies can ask you for your TFN, such as the ATO, your employer, and your bank. However, there may be financial consequences if you don’t give them your TFN, such as paying the highest marginal tax rate on your income or interest payments.

It is important to keep your TFN and personal details safe, as someone can steal your identity if they have your TFN. You must not let anyone else use your TFN, and you should only disclose your TFN to people and organizations that require it for legitimate reasons.