How we calculate
Tax withheld comes from the ATO's Schedule 1 – Statement of formulas for calculating amounts to be withheld (NAT 1004): for 2026–27 the formulas in legislative instrument LI 2026/18, and for 2025–26 the formulas that applied from 1 July 2024. These are the same formulas payroll software uses. Tax for the year uses the ATO's published tax rates, offsets and thresholds.
How we check it
The ATO publishes sample data so payroll software developers can test their calculations. Our calculator is tested against every one of those sample rows (432 for each of 2025–26 and 2026–27), covering weekly, fortnightly and monthly pays across the tax scales and Medicare levy adjustments, and it matches all of them to the dollar. Study loans, bonuses, seniors, the Medicare levy family reduction, the surcharge and HELP repayments are checked against the ATO's worked examples.
What the figures include
- Tax withheld under scales 1 to 6: tax-free threshold claimed or not, foreign residents, no TFN and Medicare levy exemptions.
- Study and training support loans (HELP and others, Schedule 8), seniors and pensioners (Schedule 9), bonuses (Schedule 5, Method A), the Medicare levy variation for families, and tax offsets claimed on a withholding declaration.
- Tax for the year: income tax, the low income tax offset, the seniors and pensioners tax offset, the Medicare levy (with low-income and family reductions), the Medicare levy surcharge and compulsory study loan repayments.
- Super at the 12% super guarantee rate, paid by your employer on top of your pay.
What they don't include yet
- Working holiday maker rates, back payments, termination payments and Fair Work award rates.
- Your exact final tax, which depends on your full income, deductions and offsets and is worked out when you lodge a tax return.
The calculations are open source and available to software and AI assistants through our API and MCP server.
This site gives general information, not financial or tax advice, and isn't affiliated with the ATO. For your own situation, check with the ATO or a registered tax agent.