What happens if you don't give your employer a TFN
Updated 13 November 2026.
If you don't give your employer your tax file number (TFN), they have to withhold tax at the top marginal rate: 47% of your pay if you're an Australian resident, or 45% if you're a foreign resident. You also can't claim the tax-free threshold.
The difference on $1,000.00 a week
| Tax withheld | Take-home pay | |
|---|---|---|
| TFN provided, tax-free threshold claimed | $138.00 | $862.00 |
| No TFN (resident) | $470.00 | $530.00 |
How to fix it
Give your employer your TFN on a Tax file number declaration, usually through their onboarding system. If you don't have a TFN yet, you can apply for one with the ATO. Extra tax withheld while you had no TFN counts towards your tax for the year and is sorted out when you lodge your return.
Check your pay on the pay calculator.