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How to Calculate the Adjusted Cost Base for a Property Sale

Published 26 June 2026 · Last updated 26 June 2026

Quick Answer

To calculate the adjusted cost base (ACB) for a property sale in Australia, start with the original purchase price, add capital improvements, and subtract any depreciation claimed. This forms the basis for calculating capital gains tax (CGT). Consult Division 43 of ITAA 1997 for capital works deductions.

Calculating the adjusted cost base (ACB) for a property sale is a crucial step in determining your capital gains tax (CGT) liability. The ACB is essentially the cost of acquiring and holding the property, adjusted for certain factors. It includes the original purchase price, plus any capital improvements made, less any depreciation claimed under Division 40 and Division 43 of ITAA 1997.

The most common misconception is that only the purchase price impacts the ACB. However, substantial changes can occur through capital improvements and depreciation. Under Division 43, capital works expenditures can increase the ACB, while depreciation claimed can decrease it. This careful balance is essential for accurate CGT calculations.

Take a practical example: Imagine you purchased a 2-bedroom apartment in Sydney in 2010 for $700,000. Over the years, you've added a new kitchen costing $50,000 and claimed $20,000 in depreciation for plant and equipment. Your adjusted cost base would be $730,000 (purchase price plus kitchen improvement minus depreciation). If you sell the property for $1,000,000, your capital gain would be $270,000.

In our experience reviewing thousands of properties across Australia, many investors overlook the impact of capital improvements. They often fail to keep detailed records, which are essential for accurate calculations. Another frequent oversight is not adjusting for depreciation already claimed, leading to incorrect CGT calculations. Investors also tend to forget incidental costs like legal fees and stamp duty, which can be added to the ACB.

The answer can differ depending on your situation. If you acquired the property before 1985, it is exempt from CGT. For properties acquired after 9 May 2017, certain depreciation rules apply. If the property is held within a self-managed super fund (SMSF), different tax implications might arise. Joint ownership necessitates splitting the ACB calculations according to ownership percentage.

Given the complexities involved, it's wise to seek professional advice. A Chartered Quantity Surveyor can provide a detailed breakdown of your property's cost base, ensuring no detail is overlooked. Working alongside your accountant, you can optimise your tax position and avoid costly errors.

  • Gather all purchase documents, including contracts and settlement statements.
  • Compile a list of all capital improvements with corresponding receipts.
  • Review your tax returns for any depreciation claimed.
  • Consult a Chartered Quantity Surveyor for a professional assessment.
  • Work with your accountant to finalise the ACB and calculate CGT.
  • Keep detailed records for future reference and potential audits.
  • Frequently Asked Questions

    What is included in the adjusted cost base?

    The adjusted cost base includes the original purchase price, capital improvements, and incidental costs like legal fees, minus any depreciation claimed.

    How does depreciation affect the ACB?

    Depreciation reduces the ACB by the total amount claimed over the property's holding period, impacting the capital gains calculation.

    Does the ACB calculation differ for commercial properties?

    Yes, commercial properties may have different depreciation rates and capital improvement costs, affecting the ACB.

    How do state taxes affect the ACB?

    State taxes like stamp duty can be included in the ACB calculation, increasing the base cost of the property.

    How is the ACB reported in a tax return?

    The ACB is used to calculate the capital gain or loss, which is then reported in your tax return under the CGT section.

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