GST on flipping houses in Australia: when it applies and the margin scheme

Most flippers spend weeks agonising over the reno budget and about four seconds thinking about GST — right up until an accountant asks whether the sale was a taxable supply and the room goes quiet. GST on flipping houses in Australia isn't something every deal has to worry about, but when it applies it's big: one-eleventh of the sale price is real money, and it can turn a tidy margin into a break-even.

The good news is that the rules are more knowable than they look. GST doesn't care about your profit at all. It keys off two things: whether you're running an enterprise, and what you actually built. Get those two questions right up front and you'll know whether GST is in your deal long before settlement. This is general information rather than advice, but it'll tell you the questions to take to your accountant.

When GST applies to flipping houses in Australia (enterprise vs one-off)

Two triggers decide whether GST is in play, and both have to line up.

The first is turnover. If your GST turnover from taxable activity is $75,000 or more in a 12-month period, you generally have to register for GST. That threshold is on gross sale value, not profit — so the sale price of a single decent flip can push you over on its own. The ATO looks at your projected turnover for the coming 12 months as well as what you've actually turned over, so a one-off flip that you never intend to repeat can still count if it's carried out as a business-like activity.

The second, and the one that actually decides most flips, is what you built. GST applies to the sale of new residential premises, and one of the ways ordinary residential premises become "new" is through substantial renovations. Under the GST rules, a substantial renovation is one where all, or substantially all, of a building is removed or replaced; it has to affect the building as a whole. Crucially, the ATO's own guidance says a cosmetic refresh (new paint, a new kitchen, a new bathroom, new floor coverings, repairs) usually isn't substantial on its own.

So the practical line for flippers is this: a paint-and-polish cosmetic flip typically doesn't create new residential premises, and the sale usually isn't a taxable supply, so GST doesn't bite. A gut job that strips the place back to the frame and replaces most of the structure can be a different story: that can be a taxable supply attracting GST at one-eleventh of the sale price. If you're genuinely unsure which side of the line your scope sits on, that's an accountant conversation before you swing a hammer, not after you've sold and can't undo it.

GST vs CGT vs income tax on the same deal

This is where people tie themselves in knots, so let's separate the three taxes cleanly, because a single flip can involve all, some, or none of them.

Income tax. For most genuine flips, the profit is taxed as ordinary income on revenue account, at your full marginal rate, not as a capital gain. I've written about why the ATO usually treats flipping profit as income, not a capital gain, and why the 50% CGT discount most people bank on generally doesn't apply. That's the tax nearly every flip has to deal with.

CGT. Capital gains tax mostly enters the picture for personal investors: someone who bought a home or a long-term investment property, renovated it over time, and later sold. If your activity is a genuine profit-making flip on revenue account, it was never a CGT asset, so CGT and its discount don't apply. Two different systems; you're usually in one or the other, not both.

GST. GST is separate again. It doesn't care whether your income-tax treatment is revenue or capital — it only asks whether you're registered (or required to be) and whether the sale is a taxable supply, which for a flip comes down to the substantial-renovations question above. You can have an income-tax bill and no GST (the common cosmetic flip), or both an income-tax bill and GST (a substantial renovation by someone over the threshold).

Keeping these three apart in your head is half the battle. They stack; they don't substitute for each other.

The margin scheme in plain English

If your sale does attract GST, the margin scheme is the mechanism that can soften the blow, and on a flip the difference is large.

Normally, GST on a taxable property sale is one-eleventh of the whole sale price. Under the margin scheme, the ATO calculates GST as one-eleventh of the margin instead — broadly, the difference between your sale price and what you paid for the property. Because a flip's margin is much smaller than its sale price, the GST bill under the scheme is a fraction of the full-price figure.

A rough illustration to show the mechanism: you buy for $600,000, do a substantial renovation, and sell the new residential premises for $780,000. Full-price GST would be one-eleventh of $780,000, about $70,900. Under the margin scheme, GST is one-eleventh of the $180,000 margin, about $16,400. Same sale, a very different bill. (Those are arithmetic examples to show how the scheme works, not a quote for your deal — your actual margin, eligibility and GST depend on your own numbers and how the property was acquired.)

Two conditions matter and both trip people up. First, eligibility depends on how you originally acquired the property. You generally can't use the margin scheme if you claimed a GST credit on the purchase, or if you bought from someone who wasn't eligible to use it themselves. Second, you and the buyer must agree in writing that the margin scheme applies, on or before settlement. Miss that written agreement and you can lose access to the scheme entirely, with no fixing it after the fact. This is exactly the sort of clause your conveyancer should be drafting into the contract from the outset, not bolting on at the last minute.

Registering (or not)

If GST is in your deal, registration follows. You register for GST (you'll need an ABN first), charge GST on the taxable sale, and in return you can generally claim GST credits on the reno costs and other expenses that carried GST: the tradie invoices, materials, agent fees. That credit side is why registration isn't pure downside: it can offset a chunk of what you pay.

If your flip is a cosmetic job that doesn't create new residential premises, and you're not otherwise running a GST-registered enterprise, you're typically not required to register for that sale. The trap is assuming "one-off" always means "no GST" — the ATO can still treat a one-off flip as an enterprise if it's carried out in a business-like way and the numbers cross the threshold. When it's marginal, the safe move is to get the call in writing from your accountant before you commit, because the cost of guessing wrong here lands after settlement, when you can no longer price it into the deal.

Model the after-tax number

Here's the mindset shift that separates flippers who keep their margin from the ones who get surprised in July: tax isn't something that happens to the deal at the end. It's a line item you can estimate before you make an offer.

Before you buy, work out which taxes actually apply to your scope. Cosmetic refresh under the threshold? Probably income tax on the profit and no GST. Substantial renovation, over the threshold? Budget for GST, ideally under the margin scheme, on top of the income tax, and factor the reno-cost GST credits back in. Then run the after-tax number, not the gross, because a deal that looks great before tax can quietly stop pencilling once GST and income tax are both in the model. That's exactly what you want to find out before you're committed.

FlipPro's full analysis builds the whole feasibility (the purchase costs, reno, holding and selling costs the tax sits on top of) so you can see the deal before the tax and stress-test it. For a directional read on the capital-gains scenario, the CGT calculator gives you a starting figure. Neither replaces your accountant, but both stop you making an offer on a number that tax was always going to shrink.

Get the enterprise and substantial-renovation questions answered early, use the margin scheme when the sale is taxable, keep every GST-bearing invoice, and GST becomes a predictable line in your feasibility instead of a nasty surprise after the deal is done.

This is general information only and not financial, tax or legal advice. GST outcomes depend on your specific circumstances and can change. Always confirm your position against current ATO guidance and get advice from a registered tax agent before you buy or sell.

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