1. Primary sources only
Every rate, threshold and concession comes from the official source — state revenue offices (Queensland Revenue Office, Revenue NSW, the SROs), the ATO, or, for insurance-based figures like LMI, the insurers' own published estimators and lender-published tables. Secondary blogs and news articles are never used as a source of rates. Each calculator page lists its sources at the bottom.
2. Dated verification, in the open
Every calculator carries a verification stamp showing the rate year it runs on, and each page's Sources section records the exact date the schedule was last checked against its source. If a page looks stale to you, tell us — the contact page reaches a human.
3. Engines tested against official worked examples
The calculation engines are covered by an automated test suite — currently more than 160 accuracy tests — that pins them to the revenue offices' own published examples: QRO's example that a $730,000 established first home pays exactly $6,555; Revenue NSW's premium base of $88,036, which our engine must reproduce from the formula rather than store; Tasmania's published $400,000 land tax example of $1,287.50; the ACT determination's cumulative amounts at every bracket boundary. The suite runs as part of every build: if a change would break a published example, the build fails and the site cannot deploy. Worked examples printed on our pages are generated by the same engines at build time, so the prose can never drift from the calculator.
4. Probed against the official calculators — to the cent
Where a revenue office publishes its own calculator, ours must match it exactly, and we probe with awkward values chosen to expose rounding rules the documentation doesn't state. Two examples of what that finds. South Australia's land tax legislation charges per "$100 or part of $100" — so $936,150 of site value owes $1.00, not the 75¢ a straight percentage gives; RevenueSA's calculator confirms it, and ours reproduces it. Western Australia's vehicle duty formula rounds its sliding rate to two decimals and then rounds the duty down to the nearest five cents — a rule stated nowhere on the rates page, discovered by probing RevenueWA's calculator with values like $35,050 (answer: $1,493.10, not $1,493.13). Most calculators on the internet approximate with percentages; the schedules don't, and neither do we.
5. Boundary semantics, taken seriously
The expensive errors in tax calculators live at the edges of brackets, where "up to", "not exceeding" and "less than" all mean different things. Our data files encode each state's actual boundary semantics: Victoria's duty bands that switch to a flat percentage of the whole price above $960,000 (so exactly $960,000 stays marginal — the SRO's ">" matters); WA's land tax step that is nil at exactly $300,000 and $300 flat at $300,001; Queensland's first home concession bands that align to the QRO's table rather than a smooth taper. Every one of these edges has a dedicated test sitting exactly on the boundary.
6. The 1 July ritual — and the mid-year watch
Australian rates move on a rhythm: state budgets in May–June, new thresholds and schemes on 1 July, indexation through the year. Every data file is re-verified each July, and again whenever a state announces a change. Some changes don't wait for the new financial year — the ACT's vehicle duty rates rise on 1 February 2027 under a determination already made, and the ACT abolished first-home duty from 1 July 2026 — so pages carrying a scheduled change say so, with the date. Where federal law has already changed future rules (the 2027 capital gains and negative gearing reforms), the affected calculators explain both regimes now rather than springing the change later.
7. Estimates labelled as estimates
Some figures are exact schedules (stamp duty); others are inherently indicative (LMI premiums vary by lender and insurer). Where a number is an estimate, the page says so plainly and explains the uncertainty rather than hiding it — and where eligibility conditions decide which schedule applies to you (first-home tests, residence requirements, foreign-person definitions), the page states the conditions instead of silently assuming them.
8. Independence
No lender, broker, insurer or agent pays Tallyroo to appear anywhere on this site, and no calculator result is shaped by a commercial relationship. When advertising runs on these pages it is clearly marked as advertising, and it never changes a number. We built the calculators we wished existed when doing our own sums — the revenue office's answer, without the lead-gen form in front of it.
The sources matter, and so does who reads them. Tallyroo is built and maintained by Rakesh Choudhary, and it publishes arithmetic rather than advice — which is precisely why every page shows its working and cites the schedule instead of telling you what to do.
Corrections
Found an error? We want it. Email us via the contact page — verified corrections ship fast and are noted on the affected page. Tallyroo provides general information only, not financial, legal or tax advice; always confirm significant decisions with the official source or a licensed professional.