Highlights

  • Using a home to earn income can reduce the proportion of any eventual Capital Gain that is exempt from tax.
  • Ordinary employee work-from-home arrangements generally differ from areas operated as dedicated Business premises.
  • The uploaded source describes separate calculations for growth before and after 1 July 2027.
  • A simplified example produces a taxable gain of approximately AUD 39,495 under the described framework.

Australian homeowners sometimes use a spare bedroom for rental income or set aside a room to operate a business. Those decisions can have consequences beyond annual income tax: an income-producing portion of a principal residence may cease to qualify for the full Capital Gains Tax (CGT) main residence exemption. The supplied research describes a new method for calculating taxable gains after July 2027.

When a Main Residence Becomes Partly Taxable

Under the existing principles described in the source, a property can be partly subject to CGT where identifiable space is used to earn assessable income. Renting a bedroom is one example; operating a dedicated consulting room or business premises is another. The taxable share commonly reflects both the floor area attributable to earning income and the period for which that use continued. Whether Mortgage interest would have been deductible for the space can be relevant to the assessment.

Working From Home Is Not Always Business Use

An employee working occasionally or regularly at a home desk does not automatically lose part of the main residence exemption. The source distinguishes ordinary home-office arrangements, where occupancy expenses such as mortgage interest are generally not deductible, from premises set aside as a place of business. A room used to meet clients or customers may be treated differently. The distinction depends on the use of the space.

How the Source Describes the July 2027 Split

The uploaded research describes changes scheduled to take effect on 1 July 2027: gains attributed to the earlier period would retain the existing 50% discount mechanism, while eligible subsequent gains would be calculated against an inflation-indexed cost base and could face a 30% minimum-tax rule. Only the non-exempt proportion enters the calculation. The source also notes that technical details for homes acquired before commencement remained under discussion as of 11 October 2026.

Illustrative Calculation: A Room Rented to a Lodger

Consider the source’s hypothetical owner, Mia, who bought a home for AUD 700,000 in 2022, rented out 15% of its floor area throughout ownership and sold it for AUD 1.15 million in 2032. The assumed 1 July 2027 property value is AUD 850,000. Under the former simplified method, 15% of the AUD 450,000 nominal gain equals AUD 67,500; applying the 50% discount leaves AUD 33,750 taxable.

Under the alternative described in the source, 15% of the AUD 150,000 pre-2027 growth equals AUD 22,500, or AUD 11,250 after the discount. Assumed Inflation of 2.5% a year increases the post-2027 cost base to about AUD 961,697, leaving a real gain of AUD 188,303. The 15% taxable portion is approximately AUD 28,245, producing AUD 39,495 in total taxable gains. The difference is about AUD 5,745, before any minimum-tax adjustment.

Key Insights

The figures are hypothetical rather than a tax assessment. They omit Acquisition and selling expenses, individual tax circumstances and detailed apportionment requirements. Relevant records include rental agreements, dates, floor plans and expense records. It also notes that existing main residence rules, including certain absence and inherited-dwelling provisions, continue to matter. Any proposed transitional calculations should be checked against final legislation and official guidance before publication or use.