Your Tax File Number (TFN) is a number issued to you by the Australian Taxation Office used to identify you or your business when you lodge your Tax Return.
The good thing about a Tax File Number is that you only ever need to apply for one for yourself! You can use this one number for each different job that you have.
You will need to provide your TFN in many situations, however the most common times you will need it us when completing your tax return, when changing employment, or when applying for a government benefit.
To find out how to apply for a TFN, please visit the ATO's information by clicking here