As in Tax File Number Declaration (or TFN Declaration).
A TFN Declaration is a form used to provide your Tax File Number (TFN) to your employer (or other payer as required) so they know how much tax to withhold from payments they make to you.
A separate TFN Declaration must be completed for each new employer you have, as such you should complete a new TFN Declaration when you start work for the first time or when you change jobs.
The most common question I get asked about this form relates to Item 8: Do you want to claim the tax-free threshold from this payer?
To give a definitive answer to this question, I would need to discuss your personal circumstances with you…however the fine print on the form tells us “Only claim the tax-free threshold from one payer at a time, unless your total income from all sources for the financial year will be less than the tax-free threshold”
A sample of the form can be found here (please note this is an external link).