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How Stamp Duty Impacts Your Property's Cost Base

Published 26 June 2026 · Last updated 26 June 2026

Quick Answer

Stamp duty is considered a capital cost and forms part of the cost base of your property for Capital Gains Tax (CGT) purposes. This means it can reduce your CGT liability when you sell the property. According to the ATO, the cost base includes acquisition costs like stamp duty, which are not immediately deductible but are essential for calculating CGT.

When you purchase an investment property in Australia, stamp duty is one of the significant upfront costs you'll encounter. This tax, levied by state and territory governments, is not just a one-time expense; it plays a crucial role in determining your property's cost base for Capital Gains Tax (CGT) purposes.

How Stamp Duty Affects Your Property's Cost Base

Under the Income Tax Assessment Act 1997, stamp duty is classified as a capital cost. This means it is added to the cost base of your property, which is used to calculate your capital gain or loss when you eventually sell the property. The cost base comprises various elements, including the purchase price, acquisition costs like stamp duty, and any capital improvements. One common misconception is that stamp duty is immediately deductible, but it's actually a non-deductible capital expense that helps reduce your CGT liability.

How This Works in Practice

Consider a scenario where you purchase a 3-bedroom house in Sydney for $950,000. The stamp duty on this purchase might be around $40,000, depending on current NSW rates. When calculating your CGT liability upon selling this property, the cost base would include the original purchase price plus the stamp duty, totaling $990,000. If you sell the property for $1.2 million, your capital gain would be $210,000 (i.e., $1.2 million - $990,000), not the full difference from the purchase price. Assuming a 37% marginal tax rate, this adjustment could save you $14,700 in CGT.

Professional Insight

In our experience, many investors overlook the role of stamp duty in the cost base, often focusing solely on purchase price and renovation costs. One thing we frequently see is investors not keeping accurate records of acquisition costs, which complicates CGT calculations later. What most investors don't realise is that every dollar added to the cost base reduces potential CGT liability, making meticulous record-keeping essential. Additionally, some investors mistakenly believe that stamp duty is deductible against rental income, leading to incorrect tax filings.

When Does the Answer Change?

  • Pre-1985 Properties: Properties acquired before 20 September 1985 are generally exempt from CGT, so the cost base considerations differ.
  • Different Ownership Structures: If a property is held in a trust or company, the treatment of stamp duty in the cost base may vary, especially concerning distributions and tax obligations.
  • Partial Year Ownership: If you buy or sell partway through the financial year, the timing of the transaction can impact the annual tax calculations.
  • State Variations: Stamp duty rates and concessions vary significantly across states and territories, affecting the initial cost and, consequently, the cost base.
  • When Should You Seek Professional Advice?

    Given the complexity of tax laws and the significant financial implications, it's wise to consult with a Chartered Quantity Surveyor and an accountant. They can ensure that all costs are accurately documented and that the cost base is correctly calculated to minimise CGT. This is especially crucial if there are unique circumstances like property improvements or changes in ownership structure.

    What to Do Next

  • Calculate Your Initial Cost Base: Include purchase price, stamp duty, and other acquisition costs.
  • Keep Detailed Records: Document all expenses related to the property acquisition and improvements.
  • Consult Professionals: Engage a Chartered Quantity Surveyor to verify your cost base calculations.
  • Review State-Specific Requirements: Check for any state-specific requirements or concessions.
  • Plan for Future Sales: Consider how current decisions will impact your future CGT liabilities.
  • Stay Informed of Legislative Changes: Tax laws can change, so keep informed of any updates that may affect your property investment.
  • Frequently Asked Questions

    Is stamp duty deductible on an investment property?

    No, stamp duty is not immediately deductible. It is a capital cost added to your property's cost base, reducing CGT liability upon sale.

    How does stamp duty vary across Australian states?

    Stamp duty rates and concessions vary significantly across states. For example, NSW may have different rates and exemptions compared to Victoria or Queensland.

    How do I report stamp duty in my tax return?

    Stamp duty is not reported as a deductible expense in your tax return. Instead, it forms part of the cost base for calculating CGT.

    Does stamp duty affect primary residences differently?

    Yes, for primary residences, stamp duty still forms part of the cost base, but CGT implications differ due to the main residence exemption.

    Can stamp duty affect my property's CGT discount eligibility?

    No, stamp duty itself doesn't affect CGT discount eligibility, but maintaining proper cost base records is crucial for accurate CGT calculations.

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