Stamp duty calculator

How stamp duty works in Australia

Stamp duty (called transfer duty in NSW and some other states) is a tax you pay when property changes hands. It's charged on the dutiable value of the property, which is the higher of the price you pay or the market value, so there's no dodging it with a mates-rates contract. Each state and territory runs its own schedule, its own concessions and its own surcharges, which is why the same purchase price produces a very different bill depending on which side of a border the house sits. For a flipper it's almost always the single biggest transaction cost of the deal, and unlike the reno it buys you nothing you can sell.

It's marginal, not a flat percentage

The mistake I see most often is someone estimating stamp duty as a round percentage of the price. It doesn't work like that. The brackets are marginal: each slice of the price is taxed at that tier's rate, and the rate climbs as the price does. In NSW, for example, transfer duty on a purchase between $372,000 and $1,240,000 is calculated as $11,152 plus $4.50 for every $100 over $372,000 under the current schedule published by Revenue NSW. On a $700,000 purchase that comes to roughly $25,900 before any surcharge. Every state has its own version of this table, so the only reliable way to get your number is to run the actual price through the calculator above or the relevant revenue office, not to eyeball a percentage.

Investor vs first-home buyer rates

This calculator returns the investor rate, because that's the number that matters for a flip. The first-home-buyer exemptions and concessions that get quoted everywhere don't apply to an investment purchase: you're buying to renovate and resell, not to live in, so you pay full freight. Off-the-plan concessions, pensioner concessions and owner-occupier thresholds aren't modelled here either. If you genuinely qualify for one of those, calculate it through the state revenue office instead, but assume the standard investor rate for any deal you're flipping.

The surcharges that catch people out

On top of standard duty, several states add a foreign purchaser surcharge for buyers who aren't Australian citizens or permanent residents (and, in some cases, for foreign-owned companies and trusts). In NSW that surcharge rose to 9% of the full purchase price from 1 January 2025, charged on top of the ordinary duty, per Revenue NSW. It's a big enough number to sink a deal on its own, and it's easy to trigger accidentally through a trust or company structure, so if there's any foreign-ownership element to how you're buying, get advice before you exchange.

When you pay, and why the timing matters

Stamp duty is due up front, not at the back end when you sell. In NSW it's generally payable within three months of the contract date (or at settlement if that's sooner), and other states run similar windows. That matters for a flip because the duty is cash you tie up on day one and don't see again until you sell, if the deal even works. It doesn't reduce your income tax as you go; instead it forms part of the property's cost base, which lowers the taxable profit when you eventually sell. Model it as an up-front cash call, and confirm your tax treatment with an accountant.

Why stamp duty decides more flips than people think

Because duty is a five-figure hit before you've painted a single wall, it sits right inside the buffer the 70% rule carves off to keep a deal safe. Underestimate it and you quietly overpay. It's one of the costs the flip ROI calculator folds into the all-in number, alongside holding costs and selling costs, so you're comparing profit after the real purchase cost rather than a headline margin. It also feeds the cost base your capital gains position is worked out from. Get the duty figure right early, and the rest of the feasibility rests on solid ground. You can see how it all comes together on a real listing in the sample analysis.

This is general information, not financial, tax or legal advice. Stamp duty rates, thresholds and surcharges change and vary by state. Figures are examples current at the time of writing. Always confirm the current duty for your specific purchase with the relevant state revenue office before you exchange.