With more older Australians looking to downsize and younger generations looking to get a foot on the property ladder, building a granny flat or a second dwelling in your backyard has become a more affordable solution.

In 2023, CoreLogic analysis of residential properties in Sydney, Melbourne and Brisbane found more than 655,000 sites suitable for constructing a granny flat.i

It has become such a popular option that there are now a host of businesses providing modular buildings as an alternative to designing and building your own.

Before taking the leap, make sure you have checked out local council regulations, restrictions and permit costs. Rules vary from council to council and usually include restrictions on the size and location.

Tax implications

It’s also important to know there are potential tax consequences – particularly capital gains tax (CGT).

While, for some, a granny flat may be considered a secondary dwelling on a property, to be eligible for a CGT exemption, there needs to be a written agreement giving someone the right to occupy a property for life.ii

The agreement can be entered into with any party – including family and friends – and will be exempt from CGT, provided the person with the ‘granny flat interest’ has reached pension age, or requires assistance with their day-to-day activities because of a disability.

Granny flat or investment property?

There are important differences between a granny flat arrangement and building a secondary dwelling on your property as an investment or renting out a room in your home.

A second home on a property that is used for short or long-term rental purposes is considered a commercial arrangement and the rent you receive is assessable income, on which you pay income tax on at your marginal tax rate.

Like most income-producing activities, you are entitled to claim the normal expense deductions against the rental income.

Granny flat arrangements, on the other hand, must not be a commercial arrangement.

Capital gains

Capital gain can be an issue that needs to be considered when setting up a granny flat arrangement. If you don’t follow the rules, you may find yourself with an unexpected tax bill when you eventually sell your home.

Usually, a granny flat arrangement is exempt from CGT provided it is not commercial in nature.

This means if the person living in the granny flat is required to make payments (such as rent) at a market rate, CGT will apply. If the individual only contributes to ongoing household costs (such as electricity and water) however, the ATO is unlikely to consider it a commercial arrangement.

To qualify for the CGT exemption, the property owner must be an individual, one or more individuals must have an eligible granny flat interest in the property, and both parties must have entered into a written and binding granny flat arrangement.

The CGT exemption only applies to creating, changing or terminating a granny flat arrangement.

Other CGT events unrelated to a granny flat arrangement, or outside the arrangement, are subject to normal CGT rules and may be liable for CGT. For example, the sale of a property previously used in a now terminated granny flat arrangement is still subject to the normal CGT rules.

Tips for a successful arrangement

While adding another dwelling to your property may increase the value of your home, it’s essential to get all the parties together to consider possible future scenarios before the written agreement is signed to avoid any potential problems further down the track.

The agreement should cover everyone involved in the arrangement, the circumstances in which the agreement can be varied or terminated and what happens if this situation arises.

It’s also sensible to discuss how any problems or financial conflicts will be resolved and to seek professional legal advice before signing.

We can help explain the tax rules if you’re interested in setting up a granny flat arrangement, so call our office today.

i Untapped granny flat potential in largest capitals could boost housing supply | CoreLogic Australia

ii Granny flat arrangements and CGT | Australian Taxation Office