In which scenario might you need to apply for a TFN?

A Tax File Number (TFN) is a unique identifier issued by the tax authority that plays a vital role in the Australian taxation system. You need a TFN primarily for tax purposes, including starting a job and lodging a tax return. When beginning employment, employers require your TFN to ensure that they withhold the correct amount of tax from your earnings. Similarly, when you lodge your tax return, having a TFN allows the tax office to track your tax obligations and facilitate any refunds you may be entitled to.

In other scenarios like joining a social club, moving to a different country, or applying for a passport, a TFN is not necessary. These situations do not relate directly to your taxation obligations or income reporting. Thus, option B is the correct choice, as it directly connects to the core responsibilities associated with taxation in Australia.