Protect your Tax File Number

Your tax file number (TFN) is used to identify you in your dealings with the Australian Taxation Office and will usually stay the same for life. It's an important part of your identity and should be kept safe.

Never quote or give out your TFN unless there is a good reason, such as completing a tax form or opening a bank account.

Only certain people are entitled to ask for your TFN including the Australian Taxation Office, Centrelink, your superannuation fund, bank or financial institution, and your employer (but only after you have started working for them).

Your TFN should never be used to establish or confirm your identity with other organisations.

Read more on the tax office website

http://www.ato.gov.au/individuals/content.aspx?menuid=0&doc=/content/00092180.htm&page=4&H4