How the TFN declaration works
Take someone on $80,000 with one job. If they claim the tax free threshold, their employer withholds about $311 a week. If they do not, it is $421 a week, $110 more every week, or $5,720 over the year. Their real tax bill is the same either way. It gets settled when they lodge a tax return.
What the declaration does
When you start a job you give your employer a tax file number declaration (NAT 3092). They use it to work out how much tax to withhold from your pay. It asks for your TFN, whether you are an Australian resident for tax purposes, whether you want to claim the tax free threshold from this payer, and whether you have a study or training loan. If you want less tax withheld, for example to claim an offset, a separate withholding declaration (NAT 3093) does that. We do not model it.
Withheld is not the final tax
The declaration changes how much comes out of each pay. The tax return sets what you owe. We work out the withholding with the ATO weekly tax table for 2026 to 27 (Schedule 1, NAT 1004). The table includes the 2% Medicare levy, so we compare it with income tax plus levy. On $80,000:
| Choice | Withheld a week | Withheld a year | Tax and levy on the return | Result at the return |
|---|---|---|---|---|
| Claim the threshold | $311 | $16,172 | $16,120 | a refund of $52 |
| No threshold | $421 | $21,892 | $16,120 | a refund of $5,772 |
| No TFN | $722 | $37,544 | $16,120 | a refund of $21,424 |
The result column assumes this is your only income and that you lodge.
The tax free threshold works for one payer at a time
The ATO form says to claim it from one payer at a time, unless your total income for the year will be less than the threshold. If you have a second job or a taxable pension, you tell your second payer to withhold at the higher rate. If you do not, you might have a tax debt to pay when you lodge. Claim it twice and each employer withholds as if it were your only job, so the $18,200 gets counted twice in your pay. Our calculator shows the no threshold figures for one job on its own. The return adds all your income together, so for a second job read the result column as a guide only.
The table also leaves out offsets. On $30,000 the weekly table withholds $1,872 a year, but the return works out $1,268.90 after the $700 low income tax offset. That is a refund of $603.10. To have an offset reduce your withholding, you give your employer a withholding declaration.
Foreign residents
If you are a foreign resident for tax purposes, you are not entitled to the tax free threshold, you cannot claim tax offsets to reduce withholding, and you do not pay the Medicare levy. The rates are 30% up to $135,000, 37% up to $190,000 and 45% above that. On $80,000 that is $24,000 of income tax and take home pay of $56,000, against $63,880 for a resident.
No TFN
If you do not give your TFN or claim an exemption, your employer has to withhold at the top rate. That is 47% for a resident and 45% for a foreign resident. On $80,000 it is $722 a week, $37,544 over the year, where the return needs $16,120. If you say you have applied for a TFN, the employer has 28 days to wait for it. After that, the top rate applies.
The study loan question
The form asks if you have a HELP, VSL, FS, SSL or AASL debt. Answer yes if you do. The repayment itself is worked out from your income when you lodge, so we show it as its own line. See how HELP repayments come out of your pay. Withholding for the loan is not in the estimate above.
What our figures leave out
Our estimate uses the weekly table, so your own payslip can differ. We also leave out the half and full Medicare levy exemption scales. The Medicare levy low income thresholds are the 2025 to 26 figures, as the Medicare levy guide explains.
Pick your choice on the calculator or see the $80,000 salary page. Income tax is covered in how Australian income tax works. This is general information, not advice.
Keep reading
How Australian income tax worksThe Medicare levy explainedSuper and your take home payHow HELP study loan repayments come out of your pay