What is cost base for CGT purposes?
Understand what makes up the cost base of a CGT asset and how it is used to calculate a capital gain or loss.
Summary
The cost base of a CGT asset is what it cost you, including incidental costs of acquiring and disposing of it, some ownership costs, and capital costs of improvements or defending your title. It is used to calculate capital gains. A reduced cost base is used to calculate capital losses.
What this means
The cost base has 5 elements: money or property given for the asset; incidental costs (such as stamp duty, legal fees and brokerage); non-deductible costs of owning the asset (such as rates and interest, for assets acquired after 20 August 1991); capital costs of increasing or preserving value or installing the asset; and capital costs of preserving or defending title.
You cannot include amounts you have claimed, or could claim, as a tax deduction elsewhere. For example, capital works deductions cannot also be included in the cost base. If the asset was acquired before 21 September 1999, indexation may apply as an alternative to the CGT discount. Cost base calculations for real property, shares, and inherited assets have specific rules.
Typical actions
- Keep records of the purchase price and all incidental costs.
- Record capital improvements separately from repairs.
- Note any amounts previously claimed as deductions.
- Consider using the ATO’s CGT record keeping tool.
- Keep records for as long as the asset is owned plus at least 5 more years.
Official ATO sources
Last checked: 25 August 2026
Cost base of assets
Explains the 5 elements of the cost base.
Calculating your CGT
Main ATO hub for CGT calculations, including cost base.
Related questions
- What is the CGT discount and how does it work?
- What is a capital loss and how can it be used?
- What records should investors keep for CGT?
- How does capital gains tax work?
Important notice: Tax Clarity is an independent information tool. This page provides general information based on official sources. It does not provide tax, legal, financial, or accounting advice. Tax rules can change, and how they apply depends on your circumstances. For advice about your situation, speak with a registered tax agent or qualified professional.
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