If you don't have a tax file number yet, don't panic. You can apply to the Australian Taxation Office to get one. 

TFNs cannot be allocated over the telephone, by facsimile, or by email. For information on how to apply for a TFN, or if you cannot find your TFN, phone the Tax Office on 13 28 16.

It is essential to apply early to ensure you have your TFN on or before your unit census date. A TFN is usually provided within 28 days of application.

If you are applying for a TFN for HECS-HELP within one month before the relevant census date, you must request a Certificate of application for a TFN from the Australian Taxation Office. You should provide the certificate to UWA as proof of your application, and it must be supplied if you have not received your TFN before the census date.

You can still enrol without a tax file number but you will need to choose the up-front payment option for your Student Contribution, and supply the tax file number later. You can do this online by completing the commonwealth assistance form on studentConnect.