Methodology

This page explains exactly how DutyMate produces a figure. The calculator and every rendered page run the same engine, so what you read here is what the tool does.

Where duty rates come from

Each state and territory sets its own transfer-duty schedule. We transcribe each one from the official revenue office — Revenue NSW, the State Revenue Office Victoria, the Queensland Revenue Office, RevenueWA, RevenueSA, the State Revenue Office Tasmania, the ACT Revenue Office and the Territory Revenue Office. The transcribed schedule is committed to a dataset that records its source URL, effective date and the date we verified it. That committed dataset is the single source of truth. Automated parsing may assist, but it never publishes on its own — a mis-read tax bracket is a credibility problem, and these schedules are small enough to check by hand.

How duty is calculated

Most states use a bracketed schedule: a fixed base amount for the band plus a marginal rate for every $100 above the band's threshold. Some rules need special handling, and we encode each one explicitly: Victoria's $960,000 to $2,000,000 band is a flat 5.5% of the whole value, not a marginal rate; Victoria also has a separate principal-place-of-residence scale for owner-occupiers up to $550,000. Queensland has a separate owner-occupier home concession. The Northern Territory is a formula — a quadratic below $525,000 and a flat percentage above. Several offices charge duty on each "$100 or part of $100", so we round the value up to the next $100 before applying the rate for those states, exactly as the office does.

Verification

Every schedule is cross-checked against the office page and at least one independent calculator, and every worked example is asserted by an automated test that runs on each build — if any figure drifts by a dollar, the build fails before it can ship. Two offices, RevenueSA and the Territory Revenue Office, block automated requests; their schedules are stable (South Australia's has been unchanged since 2012) and are cross-checked against secondary calculators and the documented formula, then re-verified from a real browser at launch. Those pages carry a "cross-checked" badge until that re-verification is recorded.

First home buyers

First-home concessions change often and differ sharply by state, so we only compute a figure where the rule is settled and public: New South Wales (full exemption to $800,000, phasing to $1,000,000), Victoria (full exemption to $600,000, phasing to $750,000), Queensland (a fixed first-home concession table for established homes, and nil duty with no cap for new builds), South Australia (nil duty with no cap for new builds), Western Australia (no duty to $500,000, then a concessional rate per $100 to $700,000 in the Metropolitan and Peel regions or $750,000 outside them) and the ACT (from 1 July 2026 the Home Buyer Concession Scheme has no income test and no value cap — eligible buyers pay no duty at any price). Tasmania's 100% exemption for established homes ended on 30 June 2026 and was not extended, so established first-home buyers there now pay the standard rate. The Northern Territory's home-buyer help runs through grants rather than a duty concession. Where a rule is in flux — WA has announced higher thresholds that are still before Parliament — we say so on the page. We never invent a phase-out number.

Loan repayments, borrowing power and LMI

Repayments use the standard amortisation formula and are exact for the rate and term you enter; the default interest rate is an editable assumption for the current market, not a quote. Borrowing power converts gross income to net using the 2026-27 resident tax scale plus a 2% Medicare levy with no offsets, then assesses your surplus at your rate plus the 3% serviceability buffer lenders apply under APRA guidance — it is an indication, not a lending decision. Lenders mortgage insurance has no public price list; our figure is an indicative estimate derived from published insurer grids and will differ from your lender's or insurer's actual quote. These three are clearly labelled as estimates wherever they appear.

Keeping it current

We re-verify the schedules against the offices at least every 1 July, when indexed rates and many concessions change, and whenever a concession threshold is announced mid-year. Each page shows the date its data was last verified. An automated staleness check fails the build if any schedule has not been re-verified within the configured window.