Last updated: June 2026 | Reading time: 8 min When I first moved to Australia for work, the very first thing my employer asked for was a Tax File Number. I had no idea what it was or where to get one — I just knew I needed it before my first payslip, or I'd be taxed at the highest possible rate with no way to get it back easily. If you're new to Australia, starting a job, or opening a bank account for the first time, your TFN is the first piece of the financial puzzle. Here's everything you need to know — including how to apply, what to do if you lose it, and what happens if you don't have one. What Is a Tax File Number? A Tax File Number (TFN) is a unique 9-digit number issued by the Australian Taxation Office (ATO) to identify you in the tax and superannuation systems. It stays with you for life — you keep the same TFN whether you change jobs, move interstate, get married, or become an Australian citizen. Think of it as your personal ID number for...