A Perth house flip case study: the numbers on a WA deal in a falling market

Every month I put one worked deal on the page, and this Perth house flip case study is the first one where the biggest risk to the deal was not a cost line at all. It was the exit. The three case studies before this were in New South Wales, regional Queensland and Victoria, and in each one the lesson lived in the buy price or the duty. Perth is different right now, because the market moved under the deal while the reno was still happening, and that is the whole story.

The deal below is illustrative. The property is a composite of the tired brick-and-tile that turns up in Perth's cheaper outer corridors, and every cost line is a real, current figure so the maths is honest even though the address is not one specific house. Where a number is an assumption, I have said so.

The deal: a tired brick-and-tile in an outer Perth corridor

The property is a three-bedroom, one-bathroom brick-and-tile house on a 580m² block in one of Perth's affordable outer south-east corridors, the kind of pocket where first-home buyers and young families are the whole market. Good bones, bad everything else: original kitchen, one dated bathroom, worn carpet, tired paint and a yard gone to weeds. Nothing structural, just old, which is the profile you want for a cosmetic flip.

On the comparable sales I pulled when I first looked, renovated three-bedders in the same streets had been selling around $640,000 to $655,000, so the after-repair value looked like roughly $650,000. The asking was $520,000 and I negotiated the buy to $470,000. Perth vendors had started to deal, and on those numbers this looked like a clean, roughly ten per cent flip. That is exactly the trap, and I will show you why.

The feasibility: a straight cosmetic exit

Before running the numbers I checked what the block could do, because the buy only makes sense against the right exit. A 580m² lot in a standard residential zone with the house mid-block did not support a subdivision without demolishing the dwelling, and a granny flat would have added cost without adding much to a sale price this corridor caps out at. A full feasibility runs the strategies a property can actually support rather than the ones you wish it could, and here it came down to one: a cosmetic renovation and resale to an owner-occupier. The margin had to come from buying well and renovating tightly.

The numbers: a full Perth house flip, line by line

Here is the whole deal on one page, the same structure the worked sample analysis lays out.

Buying it

Western Australia's transfer duty on a residential purchase in the $360,001 to $725,000 band is $11,115 plus 4.75% of the value above $360,000, so $470,000 comes to $16,340 (WA transfer duty, Department of Treasury and Finance; you can check any price on the stamp duty calculator). The first-home concessions do not apply to a flip, because you are buying it to sell, not to live in. A combined building and pest inspection runs $400 to $800, so I used a mid-range figure.

Renovating it

The kitchen and bathroom bands sit inside the renovation cost per square metre ranges the reno cost calculator uses, and a cheaper corridor keeps the whole scope lighter than it would be on a middle-ring house. The 12% contingency is not optional: on a cosmetic job you will still find something behind a wall.

Holding it (five months)

The interest is an assumption: an 80% loan of about $376,000 at roughly 6.2%, near the mid-2026 average variable rate, over a five-month hold. If the sale drags, this line grows fast, which is the whole argument of the six-month holding-cost walkthrough.

So the money going in is fixed and known: $489,290 to acquire, $70,560 to renovate and $12,250 to hold, which is $572,100 total cost in. Everything up to this point is under my control. The next line is not.

What the old comps said, and what the quarter did to them

Here is how the deal looked when I ran it on the comparable sales I started with.

Selling it, on the comps that got me into the deal

Perth metro agent commission averages around 2.4% (Which Real Estate Agent, WA fees), and I used a modest metro campaign. On those numbers the deal is $629,400 out minus $572,100 in, a pre-tax profit of about $57,300, or roughly 10% on cost. A perfectly good cosmetic flip.

Except those comps were already stale by the time the reno finished. Perth's median house price fell 7.4% in the September 2026 quarter, an $88,664 drop to $1,115,227, the steepest quarterly fall on record and the largest of any capital city, leaving the median about 8% below its March peak (Domain House Price Report, September 2026 quarter). A sale that settled before that quarter is not evidence of what your house is worth after it. The comps I bought on were describing a market that no longer existed.

Selling it, on recent settled comps after the fall

Take 7.4% off a $650,000 ARV and you are at about $602,000, so a realistic post-fall ARV is $600,000. Net proceeds drop to $580,600, and against the same $572,100 cost in, the pre-tax profit is about $8,500, a margin of roughly 1.5%. The costs did not move by a dollar. One quarter of a falling market quietly removed almost the entire profit, because the only variable that changed is the one the flipper does not control.

The lesson: in a falling market the ARV is the fragile input

Run through the app, the version of this deal priced on the old comps scored well and the version priced on recent comps scored poorly, and the difference between them is not the reno or the duty or the holding. It is one assumption about the exit. That is the point of this month's deal. In a flat or rising market you can be a little generous with the ARV and the market bails you out. In a market falling 7.4% a quarter it does the opposite: every week you hold, the number you are selling into is a little lower than the number you underwrote.

So the discipline changes. Price the ARV off comps that settled in the last six weeks, not sales from the start of the year and not current asking prices, because listings in a falling market are chasing the market down. Then haircut that figure for the trend before you offer, because by the time you sell it will have moved again. And move fast, because in these conditions time is not neutral, it is working against your exit. I wrote the pre-purchase side of this up in full in the post on flipping houses in a falling market, and the mechanics of pricing the exit are in the explainer on what after-repair value actually is.

There is also the income tax, which bites the good version and spares the bad one. A flip like this is taxed as ordinary income, not a capital gain, so there is no 50% discount (the ATO treats a genuine flip on revenue account). On the $57,300 the old comps promised, a 37% marginal rate plus Medicare would leave closer to $35,000. On the $8,500 the market actually left, there is almost nothing to tax, and nothing to show for five months of work and risk.

The verdict: take the fall off your offer, not just your ARV

The fix is not to walk away from Perth. It is to put the fall on the correct side of the ledger. The market took 7.4% off the ARV, so the only lever that gets it back is the buy, which means taking at least that much off the offer too.

Watch what buying $50,000 better does. Negotiate the same house to $420,000 instead of $470,000 and the duty falls to $13,965, the acquisition total to $436,915 and the holding interest a little lower with it, so the total cost in drops to about $518,725. Sell at the honest post-fall ARV of $600,000 for $580,600 net, and the pre-tax profit is back to about $61,875, a margin near 12% even in the down market. Same house, same reno, same soft market. The whole difference is a buy price that already had the fall built into it. Apply the 70% rule to the real $600,000 ARV, subtract the $70,560 reno, and the ceiling it points to is around $349,000, which tells you the honest comps were screaming "offer lower" the whole time. The discipline is the same one the maximum offer and price negotiation posts push: in this market you make the money entirely at the buy, and you let the vendor, not your own margin, absorb the correction.

Run this kind of deal yourself

If you take one thing from this Perth house flip case study, take the habit of pricing the exit before you fall in love with the buy, and of pricing it off what has settled this month, not this year. A deal that looks like a tidy 10% on last quarter's comps can be a break-even on this quarter's, and the costs will not warn you, because they do not change.

Start with the flip ROI calculator to get the shape of the deal, stress-test the holding-cost calculator with a realistic days-on-market, and read the full cost of flipping a house so nothing on the list surprises you. Whether you are buying in Perth or interstate, aim for the margin the profit benchmarks post argues for, and compare how differently the maths behaves against last month's Melbourne house flip case study, where the duty, not the market, was the drag. When you are ready to run a real listing end to end, the full deal analysis pulls the comps, the costs and the feasibility into one place, so you can run the numbers on your next deal before you commit a dollar. New to the whole process? The beginner's guide to flipping a house in Australia walks it end to end.

This is general information only and not financial, legal or tax advice. The deal above is an illustrative worked example; the property is a composite, the profit and deal score are indicative, and costs, duty rates, interest rates, agent fees and market values vary by property, state and time. Confirm current figures and get independent advice from a licensed agent, accountant and conveyancer before you act.

---