Methodology & Sources

Source authorities

All tax rules, thresholds, brackets, and rates used across AusTaxTools calculators are taken directly from published Australian Government sources — primarily the Australian Taxation Office (ATO) and Services Australia for benefit-related amounts. State stamp duty, land tax, and payroll tax figures come from each state revenue office.

Update cadence

We review calculators at the start of each Australian financial year (1 July), on Budget night when changes are announced — Budget 2026-27 rate and threshold changes were live on the site the same night they were handed down — quarterly for the ATO's General Interest Charge (GIC) and Shortfall Interest Charge (SIC) rates, and whenever the ATO publishes other mid-year changes (e.g., HELP indexation, super caps, Medicare levy thresholds). Event-driven legislative changes are applied when they take effect, not at the next scheduled pass. Every calculator page shows a "Last updated" date, generated from the page's revision history where available and falling back to the build date otherwise. In July 2026 we completed a full-site accuracy review — every calculator, reference page, and article was re-checked against primary sources. The full policy, including how corrections are handled, is in our editorial policy.

Where the math lives

Calculation logic lives in plain TypeScript files under src/utils/ and src/lib/apps/, separated from UI and covered by unit tests. This means every number shown can be traced back to a tested function rather than a hand-coded value in a page template. The site currently runs 220+ calculators and tools across roughly 1,700 pages, backed by an automated suite of over 4,600 tests — including anchor tests pinned to published ATO figures that fail loudly if a rate is changed accidentally. Tax rates and thresholds are defined once in a centralized src/data/taxYears/ configuration, so one verified update flows through every calculator and page that uses the figure, and every build checks internal links sitewide before it deploys.

Handling ambiguous rules

Where ATO guidance is ambiguous or a user's situation depends on facts we can't know (e.g., partial-year residency, trust distributions, edge-case depreciation), calculators use the most common interpretation and flag the assumption inline. They do not attempt to produce a number that could only be defended with professional advice.

Not financial advice

AusTaxTools provides general information only. It is not tax, legal, or financial advice, and it does not take your personal circumstances into account. For a binding answer, speak to a registered tax agent or financial adviser.