Every payslip in Australia has a "tax withheld" line — but few people know exactly how that number gets calculated, or what happens if the details on file with your employer are wrong. Here's the full mechanics.
What PAYG Withholding Actually Is
PAYG (Pay As You Go) withholding is the system through which your employer deducts an estimate of your income tax from every payslip and sends it to the ATO on your behalf — rather than you paying one large amount at the end of the year. It's a prepayment toward your final tax bill, not the bill itself.
How Employers Calculate What to Withhold
You complete a TFN declaration
When starting a job, you fill out a Tax File Number (TFN) declaration, which tells your employer your TFN, whether you're claiming the tax-free threshold, your residency status, and whether you have a HELP or other study loan debt.
Your employer determines the withholding scale
Based on your declaration, your employer applies one of several ATO withholding scales — Scale 1 for residents claiming the threshold, Scale 2 for residents not claiming it (common for a second job), Scale 6 for working holiday makers, and separate schedules for foreign residents.
The right tax table is applied
The ATO publishes separate withholding tables for each pay frequency (weekly, fortnightly, monthly). Your employer looks up your gross pay for the period in the relevant table and withholds the corresponding amount.
Amounts are reported and remitted
Every pay event is reported to the ATO via Single Touch Payroll (STP) — this is why your income statement now appears automatically in myGov rather than requiring a paper payment summary. Employers then remit the withheld amounts to the ATO, generally quarterly (via BAS) for small employers or monthly for larger ones.
What Happens With No TFN
You have 28 days from starting a job to provide your TFN. If you haven't by then, your employer is required to withhold at the top marginal rate plus Medicare Levy — 47% for Australian residents, 45% for foreign residents — regardless of how much you actually earn, until a valid TFN is provided. This is a significant, immediate cash-flow hit, so it's worth prioritizing over almost anything else when starting a new job.
How HELP and Study Loan Debts Affect Withholding
If you've declared a HELP, VET Student Loan, or other study/training support loan debt on your TFN declaration, your employer withholds an additional amount on top of standard PAYG, using a separate schedule (Schedule 8). This means your compulsory repayment is collected progressively through the year rather than landing as one number at tax time — see our Take-Home Pay Calculator for how HECS-HELP repayment interacts with your take-home pay under the current marginal system.
Worked Example
A resident earning $70,000/year, paid fortnightly, having claimed the tax-free threshold (Scale 1), with no HELP debt:
| Item | Amount |
|---|---|
| Fortnightly gross pay | $2,692 |
| Annualized income | $70,000 |
| Estimated annual withholding (tax + Medicare) | ≈ $13,188 |
| Withholding per fortnight | ≈ $507 |
This is an estimate collected every fortnight throughout the year — it's reconciled against your actual liability when you lodge your tax return.
See your exact take-home pay after PAYG withholding.
Use the Take-Home Pay Calculator →Withholding ≠ Final Tax
This is worth repeating: PAYG withholding is an estimate, calculated from standard tables that can't account for every individual circumstance — deductions you plan to claim, other income, or offsets you're entitled to. Your actual liability is only settled when you lodge your return. Over-withheld through the year? You get a refund. Under-withheld — common with a second job, or investment income with no withholding at all? You'll owe a balance.
Frequently Asked Questions
Related Australia Guides & Calculators
This is a simplified overview of the standard PAYG process. Actual withholding tables have additional nuances for irregular pay, allowances, and leave payments. Verify your specific situation with the ATO or a registered tax agent.