How Every Figure on This Site Is Calculated

One engine, every number

Every calculator and every tax table on this site draws from a single calculation engine. No figure is typed in by hand: the weekly, fortnightly and monthly tables are generated from the same code that powers the calculators. A rate exists in exactly one place, so when it changes, it changes everywhere at once, and a table can never drift out of step with the calculator.

What the engine implements for 2026-27

• Resident tax scale. Tax free to $18,200, then 15% on $18,201–$45,000 (the cut from 16%, legislated to start 1 July 2026), 30% on $45,001–$135,000, 37% on $135,001–$190,000 and 45% above $190,000. Where the tax-free threshold is not claimed, the 0% band is removed and 15% applies from the first dollar.
• Non-resident scale. 30% from the first dollar to $135,000, then 37% to $190,000 and 45% above. No tax-free threshold, no Medicare levy, no low income tax offset.
• Working holiday maker scale. 15% to $45,000, then the resident rates above that.
• Medicare levy. 2% of taxable income for residents, with the single-person low-income phase-in: nil at or below $28,011, then 10 cents in the dollar until the levy reaches the full 2% at $35,013. These are the most recently confirmed single thresholds; they are indexed each year and the engine is updated when the ATO publishes the new figures.
• Low income tax offset (LITO). Up to $700 for taxable incomes under $37,500, phasing down to nil at $66,667. Applied automatically for residents, capped at the tax otherwise payable.
• HELP and other study loans. The marginal repayment system that started 1 July 2025: no repayment at or below $69,528, 15 cents per dollar of income between $69,528 and $129,717, and 17 cents per dollar above $129,717, using the 2026-27 indexed thresholds.
• Super guarantee. 12% of gross salary, paid on top of the wage. Where a package is marked as super-inclusive, the engine backs the 12% out first and taxes the remainder.

Per-pay figures are annualised approximations

For weekly, fortnightly and monthly results, the engine annualises the income, calculates the full year's tax, and divides by the number of pays. The ATO's official withholding schedules work differently: they apply a formula to each individual pay event and round to whole dollars. The two methods produce payslip figures that can differ by a few dollars each pay, and both settle to the same annual tax when the return is assessed. The same caveat appears on every tax table page, because it applies to every per-pay figure on the site.

Where the rates come from

Every rate and threshold traces to a published ATO source. The main ones are the resident tax rates, the study and training support loan repayment thresholds and the broader ATO tax rates and codes pages. Where a change has been legislated but not yet started, the site uses the legislated figure for the year it applies to and says so, as with the 15% rate above.

The 1 July update ritual

Rates change at the start of each financial year, so each 1 July every constant in the engine is rechecked against the ATO's pages: the tax scales, the Medicare thresholds, the HELP thresholds and the super guarantee rate. Because the tables are generated rather than transcribed, updating the engine updates every page. Indexed thresholds that the ATO confirms later in the year are picked up when published.

Known limitations

These estimates are deliberately simple, and it helps to know exactly where they stop:

• The engine treats your gross salary as your taxable income. Deductions, salary packaging and reportable fringe benefits are not modelled.
• LITO is the only offset included. SAPTO and other offsets are not modelled.
• Medicare uses the single-person thresholds only. Family and seniors thresholds, and the Medicare levy surcharge, are not modelled. The exemption option removes the levy entirely.
• Family Tax Benefit and other government payments are outside scope.
• Lump sums, termination payments and capital gains are not handled.
• Everything on this site is an estimate for general guidance. Your actual tax is settled at assessment, and only the ATO or a registered tax agent can give you a personal answer.