Claim interest on a main residence against CGT on sale Sometimes a property which has been the main residence for only part of the time held will attract CGT when sold. This may be because You have moved into a rental property, and/or Your main residence has been rented out, and/or You have run a business from your main residence. Not many know that interest and other costs which have not been otherwise claimed can be used to reduce the CGT when the property is sold. This includes costs incurred while it was a main residence and not income producing. See s 110-15(3) ITAA97 The 3rd element of the cost base of a property: Element three: Non-capital costs you incur in connection with your ownership of a property which you acquired post 20 August 1991; for example - interest on money borrowed to acquire an asset, costs of maintaining, repairing or insuring the asset, rates and land tax. Don’t forget to include any borrowing costs not already claimed - such as LMI which is often a large expense.