Anyone who is working in Australia or is using Govt services like Centrelink should have a tax file number. This identifies you to the ATO (Australian Taxation Office) and is your personal number for life. This number is used to identify you with other services listed below and will link to your TFN and Mygov account.
To apply go to: https://www.ato.gov.au/individuals/tax-file-number/apply-for-a-tfn/
Do not share your TFN with anyone else as your identity can be stolen
There are only a few people and places that can ask for your TFN, including:
•The ATO
•Centrelink
•Your bank
•Your employer after you start a job
•Your super fund
•Your registered tax agent.
•Share trading, investment account.