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What is the Tax Treatment of a Knock-Down Rebuild?

Published 26 June 2026 · Last updated 26 June 2026

Quick Answer

The tax treatment of a knock-down rebuild involves several considerations, including GST on new builds, capital gains tax (CGT) implications, and depreciation opportunities. Developers must understand how GST credits apply to construction costs and how CGT affects the sale of newly built properties. Consulting with a Chartered Quantity Surveyor can help navigate these complexities.

Knock-down rebuilds, a popular choice for developers and investors looking to maximize property value, involve specific tax treatments that can significantly impact financial outcomes. Understanding these tax implications is crucial for optimizing your investment strategy.

Under Division 43 of ITAA 1997, capital works deductions apply to the construction of new buildings. These deductions, often referred to as building write-offs, allow developers to claim a percentage of construction costs over a set period. However, it's important to note that the demolition of the old structure typically does not attract a deduction unless it forms part of the new development's construction costs.

The most common misconception is around the GST treatment. For new residential premises, GST is applicable, and developers can claim GST credits on construction costs. However, when the property is sold, GST is payable on the sale price. This can affect cash flow and overall profit margins if not managed correctly.

To see how this plays out, consider a developer purchasing a property for $800,000 in Melbourne, demolishing the old structure, and constructing a new duplex. The construction cost amounts to $1,200,000. Under Division 43, the developer can claim annual capital works deductions. If the developer sells the new units for $2,000,000 each, GST of $200,000 per unit is payable. At a 37% marginal tax rate, this results in a net tax obligation of $148,000 per unit after claiming GST credits and considering deductions.

In our experience reviewing thousands of properties across Australia, many developers overlook the impact of holding costs during the construction phase and how they interact with GST claims. Another common oversight is the timing of GST payments, which can strain cash flow if not anticipated. Additionally, the opportunity to leverage depreciation on plant and equipment within the new build is often underutilized, particularly for high-value items.

The answer can differ depending on your situation. For instance, if the original property was purchased before 1987, the capital works deduction rules change significantly. Similarly, if the development is undertaken within a self-managed superannuation fund (SMSF), different tax treatments may apply. The GST margin scheme can also alter the GST payable on sales, and partial year ownership can affect both CGT and depreciation claims.

Given the complexities involved, consulting with a Chartered Quantity Surveyor and an accountant is essential. These professionals can navigate the nuances of GST, CGT, and depreciation, ensuring you maximize your investment's tax efficiency.

  • Review your property's eligibility for capital works deductions under Division 43.
  • Consult with a Chartered Quantity Surveyor to prepare a detailed depreciation schedule.
  • Evaluate the GST implications of your development, including potential credits.
  • Plan for CGT on the sale of newly constructed properties.
  • Discuss your overall tax strategy with an accountant to optimize outcomes.
  • Stay informed about changes in legislation that might affect your investment.
  • Frequently Asked Questions

    Is GST applicable on knock-down rebuilds?

    Yes, GST is generally applicable when selling new residential premises. Developers can claim GST credits on construction costs but must remit GST on sales.

    How does CGT apply to a knock-down rebuild?

    CGT applies to the sale of the new property. The gain is calculated based on the sale price minus the cost base, which includes the original purchase price and construction costs.

    Can I claim depreciation on the new build?

    Yes, under Division 43, you can claim capital works deductions and under Division 40 for plant and equipment. A depreciation schedule is essential.

    Are there state-specific taxes to consider?

    Yes, some states may have specific land taxes or stamp duties that could apply, impacting overall costs.

    How are tax returns affected by knock-down rebuilds?

    You must report any capital gains or losses and GST obligations in your tax return. A detailed depreciation schedule should be included to optimize deductions.

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    Written by Koste Team · Koste Chartered Quantity Surveyors · AIQS Member · RICS Member · TPB Registered · 1300 669 400 · info@koste.ai