---
title: Subdividing Your Backyard in Melbourne | Property Tax Advice
description: Subdividing your backyard? The main residence exemption does not follow a lot sold separately, and the margin scheme is not a tax on profit. A CPA guide.
---

[Accounting & Tax Blog for Melbourne SMEs | 42 Advisory](https://42advisory.com.au/42-advisory-blog)

# [Subdividing Your Backyard in Melbourne | Property Tax Advice](https://42advisory.com.au/42-advisory-blog/subdividing-your-backyard-tax-advice)

 Written by [Sergiy Kucherenko](https://42advisory.com.au/42-advisory-blog/author/sergiy-kucherenko) | 22/Dec/2025

TL;DR

Subdividing your backyard does not trigger capital gains tax by itself. Selling the new lot usually does. The main residence exemption does not follow a lot sold separately from the house, and the GST margin scheme taxes the difference between sale price and original land cost, not your development profit.

The most expensive mistake we see on backyard subdivisions is not a calculation. It is an assumption: that the main residence exemption follows the block you sell off.

It does not. Subdividing backyard land for tax purposes in Australia turns one asset into two, and the rules that exempted your home stop at the boundary of the lot the house sits on. Owners across Melbourne's south-east, from Bentleigh East and Hughesdale through to Mount Waverley and Ashwood, are discovering this after the contract is signed rather than before.

This guide sets out what actually applies: when the profit is a capital gain and when it is ordinary income, how the GST margin scheme is calculated under the GST Act, when registration is compulsory, and what the purchaser is required to withhold at settlement.

Victorian dwelling approvals, July 2026

4,642

Up 9.7 per cent on the month, seasonally adjusted

National dwelling approvals, July 2026

17,687

Down 3.6 per cent on the month, seasonally adjusted

Source: [ABS, Building Approvals, Australia, July 2026](https://www.abs.gov.au/statistics/industry/building-and-construction/building-approvals-australia/latest-release), released 1 September 2026.

## Does subdividing your backyard trigger capital gains tax?

Subdividing land is not a capital gains tax event in itself. The original block is split into separate assets, the original cost base is apportioned between them on a reasonable basis, and each new lot keeps the acquisition date of the original parcel. CGT applies when a lot is sold.

The split is the point most owners get right and the consequences are the part they miss. Registering a plan of subdivision creates two assets where there was one, but no gain is crystallised at that moment. The Australian Taxation Office confirms that the cost base of the original land is divided between the subdivided blocks on a reasonable basis, and that the date you acquired each block is the date you acquired the original parcel. See the [ATO guidance on subdividing land](https://www.ato.gov.au/individuals-and-families/investments-and-assets/property-and-land/land-vacant-land-and-subdividing/subdividing-land).

That inherited acquisition date matters. A block bought in 2009 and subdivided in 2026 still satisfies the 12 month holding requirement for the 50 per cent CGT discount, provided the profit is on capital account. Apportionment is usually done by area or by relative market value. Area is simpler; relative value is more defensible where the front lot carries the dwelling and the rear lot does not. Keep the working papers, because the cost base you claim on sale is only as good as the evidence behind it.

## Can you claim the main residence exemption on a subdivided block?

Usually not. The main residence exemption covers adjacent land only when that land is sold together with the dwelling. A subdivided lot sold on its own is fully subject to capital gains tax, even though the house on the retained lot stays exempt. The exempt area cannot exceed 2 hectares in total.

This is the provision that undoes most backyard projects. Section 118-165 of the ITAA 1997 switches off the exemption for a CGT event that happens to adjacent land without also happening to the dwelling. The ATO puts it plainly in its capital gains tax guidance on [land adjacent to the dwelling](https://www.ato.gov.au/forms-and-instructions/capital-gains-tax-guide-2020/part-a-about-capital-gains-tax/real-estate-and-main-residence/land-adjacent-to-the-dwelling): if you sell any of the land adjacent to your dwelling separately from the dwelling, the land is not exempt.

So the common plan, keep the house and sell the back half, produces a fully taxable gain on the back half. The gain is calculated on the apportioned cost base, not on the whole original purchase price, which is why owners who assumed an exemption are often surprised twice: once by the tax, and once by how small the deductible cost base turns out to be.

Two further limits apply. The adjacent land must have been used mainly for private or domestic purposes in association with the dwelling, and the exempt area, including the land under the house, cannot exceed 2 hectares. The ATO sets out the apportionment method for larger holdings under [a home on more than 2 hectares](https://www.ato.gov.au/individuals-and-families/investments-and-assets/capital-gains-tax/property-and-capital-gains-tax/your-main-residence-home/home-on-more-than-2-hectares). Neither limit rescues a separately sold lot.

Modelling this before the plan of subdivision is lodged is the whole value of early advice. Our [property tax accounting](https://42advisory.com.au/services/property-tax-accounting-melbourne) work on these projects starts with the disposal sequence, because the order in which lots are sold changes the answer.

## When is a backyard subdivision taxed as income instead of a capital gain?

A subdivision is taxed as ordinary income when the owner entered into it intending to make a profit and the activity amounts to a business or a commercial transaction. That treatment removes access to the 50 per cent CGT discount. A single one-off project by an individual can still meet the test.

There are three possible characterisations, and the gap between them is worth more than most owners expect. A mere realisation of a capital asset is taxed under the CGT rules, with the discount available after 12 months. A profit-making undertaking or scheme is taxed as ordinary income under section 6-5 of the ITAA 1997, with no discount. A business of property development goes further again: the land becomes trading stock.

The ATO applies the factors in Taxation Ruling TR 92/3 to decide which applies. Its published position on the [tax consequences on sales of property](https://www.ato.gov.au/businesses-and-organisations/assets-and-property/property/tax-consequences-on-sales-of-property) lists the entity involved, the scale and complexity of the work, the costs incurred before sale, the parties engaged, the purpose in acquiring the land, and the holding period.

In practice, the dividing line sits near construction. Selling a vacant rear lot to a builder, with nothing done beyond the plan of subdivision and the required services, sits comfortably on capital account for most long-term owner occupiers. Borrowing to build a townhouse, engaging a project manager and marketing the finished dwelling looks like a commercial transaction, and the ATO treats it accordingly. Where the same transaction produces both an income amount and a capital gain, section 118-20 prevents the profit being taxed twice.

Structure decisions follow the characterisation rather than the other way around, which is why we handle them inside a [tax planning](https://42advisory.com.au/services/tax-planning-melbourne) engagement before the first contract is signed. Our post on [property tax traps to avoid](https://42advisory.com.au/42-advisory-blog/property-tax-accountant-melbourne-avoid-ato-traps) covers the wider set of errors we see on Melbourne property files.

## How is GST calculated under the margin scheme?

The margin is the sale price less what the seller originally paid for the land, and GST is one eleventh of that margin. Development, construction, holding and selling costs do not reduce it. The margin scheme is not a tax on development profit, and it is not available for every property.

This is the single most misdescribed rule in Australian property content, including in the earlier version of this page. Under sections 75-5 and 75-10 of the GST Act, the margin is the amount by which the consideration for the supply exceeds the consideration for the seller's acquisition of the property. The ATO's guidance on the [methods to calculate the margin](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/in-detail/your-industry/property/gst-and-the-margin-scheme/methods-to-calculate-the-margin) is explicit that development costs, construction costs, legal fees and stamp duty are excluded from that acquisition figure.

The scheme is also conditional. It requires written agreement between the parties on or before settlement, and it is unavailable where the property was acquired through a fully taxable supply on which GST was calculated without the margin scheme. A purchaser who buys under the margin scheme cannot claim an input tax credit on the property. The [ATO margin scheme guidance](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/in-detail/your-industry/property/gst-and-the-margin-scheme) sets out the eligibility conditions in full.

### Worked example: a Bentleigh East rear lot

An owner bought a family home on a 743 square metre block in 2009 for $620,000. In 2026 they subdivide, retain the house on the front lot, build a townhouse on the rear lot for $580,000 including GST, and sell it for $1,150,000 including GST. Subdivision, council and professional costs come to $60,000. Apportioning the original purchase price by area, 40 per cent of the block, gives an acquisition figure of $248,000 for the rear lot.

| GST calculation | Amount |
| --- | --- |
| Sale price, including GST | $1,150,000 |
| Less apportioned acquisition cost of the rear lot | $248,000 |
| Margin under section 75-10 | $902,000 |
| GST payable at one eleventh of the margin | $82,000 |
| GST without the margin scheme, one eleventh of the sale price | $104,545 |
| Development profit, being sale price less land, build and project costs | $262,000 |
| GST if the margin were that profit, the common misreading | $23,818 |

The margin scheme saves $22,545 against the full consideration method. It does not save $58,182, which is the gap between the correct liability and the figure an owner reaches by treating the margin as profit after build costs and fees. A feasibility built on the wrong one of those numbers is out by roughly the cost of the subdivision itself.

Construction remains creditable. The $580,000 build generates input tax credits of $52,727, claimable through the business activity statement while the work is under way. Managing that timing is ordinary [BAS and IAS lodgement](https://42advisory.com.au/services/bas-ias-accountant-services-melbourne) work, and getting the reporting cycle right is what keeps a build funded. Our [BAS and tax guide for south-east Melbourne](https://42advisory.com.au/42-advisory-blog/bas-and-tax-guide-for-south-east-melbourne-small-businesses) covers the lodgement calendar.

## Do you need to register for GST to sell a subdivided block?

Only if the subdivision amounts to an enterprise and GST turnover reaches $75,000 or more. Both conditions must be met. Registration is required within 21 days of the threshold being crossed. A sale that is a mere realisation of a private asset is not an enterprise and does not require registration.

The earlier version of this page compressed those two tests into one, and the compression matters. The $75,000 figure is a turnover threshold that applies once you are carrying on an enterprise. It is not a rule that every property sale above $75,000 attracts GST. Selling the family home, or a genuinely capital lot carved off it, is not an enterprise. The ATO sets out the enterprise test in Miscellaneous Taxation Ruling MT 2006/1 and the turnover tests in its guidance on [registering for GST](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/registering-for-gst).

Turnover is tested two ways: current turnover, being the present month plus the previous 11, and projected turnover, being the present month plus the next 11. A single townhouse sale will clear $75,000 comfortably, so for any build and sell project the real question is the enterprise question, not the arithmetic. Registering 21 days after the threshold is crossed is the deadline, not the plan. Registering before the first creditable acquisition is what preserves the input tax credits on the build.

Finance sequencing sits alongside this. Lenders assess a subdivision differently once an entity is registered and the project reads as a development, which is a conversation worth having with our [residential finance](https://42advisory.com.au/finance/residential-finance-services-melbourne) team before an application is lodged.

## GST at settlement: what the purchaser withholds

For contracts entered into on or after 1 July 2018, purchasers of new residential premises and potential residential land must withhold an amount at settlement and pay it directly to the ATO under Schedule 1 to the Taxation Administration Act 1953. The seller receives the balance. This catches subdivided lots, and it is the obligation most often missed on a first project.

| Supply | Amount withheld |
| --- | --- |
| Taxable supply, margin scheme not applied | One eleventh of the contract price |
| Taxable supply under the margin scheme | 7 per cent of the contract price |

On the Bentleigh East example, the purchaser withholds 7 per cent of $1,150,000, being $80,500. The seller's actual liability is $82,000, so the withheld amount is credited on the activity statement and $1,500 is paid with the BAS. The cash never passes through the seller's account, which is exactly the point owners need to understand before they commit the sale proceeds to the next purchase.

The seller also carries a notification duty. A written notice must be given to the purchaser before settlement stating whether withholding is required and, if so, the amount and the supplier's details. Failing to give that notice is a separate offence. The ATO's [guide for suppliers on GST at settlement](https://www.ato.gov.au/businesses-and-organisations/gst-excise-and-indirect-taxes/gst/in-detail/your-industry/property/gst-at-settlement-a-guide-for-suppliers-and-their-representatives) sets out the required content of the notice.

### Planning a subdivision in Melbourne's south-east?

The characterisation, the structure and the disposal sequence are all decided before the plan of subdivision is lodged. Afterwards, the options narrow.

[Contact us](https://42advisory.com.au/contact-us)

## What to settle before you subdivide

Most of the tax outcome is fixed by decisions made before any physical work starts. These are the questions worth answering in writing, with figures attached.

- Is this a mere realisation, a profit-making scheme, or a business? Document the reasoning now, while the evidence is contemporaneous.
- Which lot is sold, and is the dwelling sold with it? The answer decides whether the main residence exemption is available at all.
- How will the original cost base be apportioned, and what evidence supports that method?
- Does the project constitute an enterprise, and when must GST registration be in place to protect input tax credits?
- Is the margin scheme available, and has written agreement been built into the contract of sale?
- Has the feasibility been run on net proceeds after GST, income tax and withholding, rather than on the headline sale price?
- Have Victorian land tax and duty consequences been checked with the State Revenue Office and your conveyancer?

State taxes sit outside the federal rules covered here, and they move. Duty, land tax and vacant residential land tax are administered by the State Revenue Office of Victoria and should be confirmed for your circumstances before you commit. We work with owners across the south-east from our Chadstone office, and our [accountants in Oakleigh](https://42advisory.com.au/accountants/oakleigh) page covers the surrounding suburbs.

## Key takeaways

| Issue | Position |
| --- | --- |
| Subdividing the block | Not a CGT event. Cost base apportioned, original acquisition date retained. |
| Main residence exemption | Lost on any lot sold separately from the dwelling. |
| Income versus capital | Profit intention plus commercial activity means ordinary income and no 50 per cent discount. |
| Margin scheme | Sale price less original land cost. Build costs do not reduce the margin. |
| GST registration | Enterprise test first, then $75,000 turnover. Register within 21 days. |
| Settlement | Purchaser withholds one eleventh, or 7 per cent under the margin scheme. |

If you are weighing a subdivision this financial year, the sequence that protects the most value is: characterise the project, fix the structure, then lodge the plan. Reversing that order is what turns a good block into an expensive lesson. The changes proposed in our note on the [2026 CGT reform](https://42advisory.com.au/42-advisory-blog/2026-cgt-reform-small-business-and-start-up-carve-outs) are worth reading alongside this if your timing is flexible.

### Model the tax before you lodge the plan

We will work through the characterisation, the GST position and the net proceeds on your actual figures, in one meeting.

[Book a meeting](https://42advisory.com.au/meetings/42advisory/initial-meeting-online)

**Disclaimer:** The information provided in this article is general in nature and does not constitute specific tax, legal, or financial advice. We recommend seeking professional advice tailored to your individual circumstances. Rates, thresholds and references were verified on 22 September 2026 and apply to the 2026-27 income year. 42 Advisory is a CPA firm and Registered Tax Agent.

## Frequently asked questions

### Do I pay tax if I subdivide my property?

Not on the subdivision itself. Splitting a block is not a capital gains tax event in Australia. Tax arises when a lot is sold, either as a capital gain or, where the project was undertaken for profit as a commercial venture, as ordinary income.

### What are the tax implications of subdividing land in Australia?

Three apply together: capital gains tax or income tax on the profit, GST if the activity is an enterprise with turnover of $75,000 or more, and withholding by the purchaser at settlement on new residential premises and potential residential land. State duty and land tax apply separately.

### Can I avoid capital gains tax by subdividing my main residence?

No. The main residence exemption applies to adjacent land only when it is sold together with the dwelling. A subdivided lot sold on its own is fully taxable, even if you have lived in the house for decades and the retained lot remains exempt.

### Do I need to register for GST to sell a subdivided block?

Only if the sale forms part of an enterprise and GST turnover reaches $75,000 or more. A one-off sale that is a mere realisation of a private asset is not an enterprise. Where registration is required, it must happen within 21 days.

### Is subdividing your block worth it after tax?

It depends on whether the profit is a discounted capital gain or ordinary income, and on whether GST applies. On a build and sell project, GST and income tax together commonly absorb a large share of the headline profit, so the feasibility should be run on net proceeds from the outset.

[View full post](https://42advisory.com.au/42-advisory-blog/subdividing-your-backyard-tax-advice)

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