Methodology and sources
One engine, one table per year
Every calculator uses the same calculation engine. Rates, thresholds and offsets for each income year are stored in one table, so a change from the ATO updates every tool at once. Money is calculated to the cent and displayed rounded to the cent; tax brackets are applied to whole dollars, as in the ATO's tables.
Testing
Before release the engine is tested against official worked examples, including the ATO's 2026–27 study and training loan repayment examples ($2,527.80, $10,276.99 and $25,478), the bracket amounts in the ATO resident and working holiday maker tables, and hand-checked low income tax offset and Medicare levy values.
Rates used for 2026–27
| Resident tax | 0% to $18,200; 15% to $45,000; 30% to $135,000; 37% to $190,000; 45% above |
|---|---|
| Foreign resident tax | 30% to $135,000; 37% to $190,000; 45% above |
| Working holiday makers | 15% to $45,000; 30% to $135,000; 37% to $190,000; 45% above (ATO Schedule 15) |
| Low income tax offset | $700; reduces 5c per $1 from $37,500 to $45,000, then 1.5c per $1 to nil at $66,667 |
| Medicare levy | 2%; singles threshold $28,011 with 10% shade-in (latest published threshold) |
| Study loans | Nil to $69,528; 15c per $1 above to $129,717; $9,028 + 17c per $1 to $186,050; 10% of total above |
| Super guarantee | 12% of qualifying earnings, due in the fund within 7 business days of payday |
| GST | 10%; registration threshold $75,000 |
What we don't model
Work-related and other deductions; the proposed $1,000 instant deduction for work expenses (not modelled until confirmed by the ATO); Medicare levy surcharge; family and seniors Medicare thresholds; tax offsets other than LITO; Division 293 tax; reportable fringe benefits outside the HELP calculator; PAYG withholding tables (our results are annual positions, not per-pay withholding); award-specific overtime and penalty rates; public holidays in business-day counts.
Sources
- ATO — Tax rates: Australian resident
- Moneysmart — Income tax (2026–27 rates)
- ATO — Study and training loan repayment thresholds and rates
- ATO — Schedule 15: working holiday makers
- ATO — Payday Super for employers
- ATO — Tax tables
- Fair Work Ombudsman — Pay slips
- Fair Work Ombudsman — Record-keeping
- ATO — GST
Last reviewed: 12 November 2026.