Renting Out an Existing Granny Flat After You Buy

Plenty of properties on the market already come with a self-contained granny flat, cottage or secondary dwelling in the backyard, and for buyers thinking about rental income it can look like an instant win. In practice, whether you can actually rent that structure out as a separate tenancy, and how much work is involved in doing it properly, depends on a handful of things a previous owner may never have dealt with. Before you factor a second rental income stream into your budget, it pays to work through the approvals, insurance and tenancy questions during your due diligence period rather than after settlement.

Confirm the Granny Flat Was Actually Approved

The single biggest risk with an existing secondary dwelling is that it was built without council approval, or approved for one purpose and used for another. A structure marketed as a "granny flat" might have been approved only as a garage, studio or storage building, with a kitchen and bathroom added later without a permit. Ask the seller's agent for the building approval or occupancy certificate specific to the secondary dwelling, not just the certificate for the main house, and have your conveyancer check council records as part of standard property searches during a residential purchase. An unapproved structure can affect insurance, finance and your ability to legally rent it out at all.

Check Zoning and Occupancy Rules Before You Advertise

Most states allow secondary dwellings to be rented to unrelated tenants, but the rules on minimum lot size, maximum floor area and how many separate households can occupy one lot vary by council and by state. Some planning schemes still restrict granny flats to family members or dependents only, while others have relaxed this in response to rental supply pressure. This is genuinely local information, so check with the relevant council or your conveyancer rather than assuming the rules from a previous property or a different state apply. If the property sits near a state border or in a council area you are unfamiliar with, it is worth raising this specifically with whoever is handling your property transfer paperwork.

Understand How One Title Affects Two Tenancies

Because a granny flat sits on the same title as the main house rather than on its own subdivided lot, you will typically be the landlord for both dwellings under separate tenancy agreements, even if you also live in the main house. This means two sets of condition reports, two bond lodgements and two sets of obligations under your state's residential tenancy legislation. If you are buying with the intention of living in the house while renting the granny flat, some lenders and insurers treat this differently to renting out the whole property, so it is worth discussing your specific structure with your bank and insurer before you commit rather than after you have already signed a lease with a tenant.

Insurance Needs to Reflect the Actual Use

A standard owner-occupier home and contents policy usually will not automatically extend to cover a portion of the property being rented to a third party. Once you have a paying tenant in a granny flat, most insurers expect you to hold landlord insurance for that dwelling, or to declare the arrangement so your combined policy reflects both uses. Failing to update your insurance is one of the more common oversights buyers make when they inherit a granny flat setup, and it can leave you exposed if something goes wrong during a tenancy rather than being a simple owner-occupier claim.

Factor in Rates, Water and Utility Metering

Check whether the granny flat has its own separate electricity, gas and water metering, or whether everything runs through the main house meter. Separate metering makes it far easier to bill a tenant directly for usage, while shared metering means you will usually need to either absorb the cost or build an estimated utility contribution into the rent. Council rates and water access charges are levied on the property as a whole rather than per dwelling, so these do not change simply because you are renting out part of the site, but they are worth confirming during settlement adjustments so nothing is missed.

Income Tax and the Main Residence Exemption

If you live in the main house and rent out the granny flat, the rental income is generally assessable and related expenses may be deductible in proportion to the space used for income-producing purposes. This arrangement can also affect the capital gains tax main residence exemption when you eventually sell, because part of the property has been used to produce rent rather than purely as your home. The ATO's guidance on eligibility for the main residence exemption sets out how partial income use is treated, and this is a good example of where a quick conversation with your accountant before you start renting is worth more than guessing. This is general information rather than personal tax advice, and your accountant can confirm how it applies to your situation.

Get the Paper Trail Right From Settlement

If you are planning to rent out an existing granny flat from the day you settle, it helps to have your conveyancer flag the arrangement early so relevant searches, such as confirming there is no outstanding notice or order relating to the secondary dwelling, are completed before exchange rather than discovered afterwards. Buyers in New South Wales and Victoria in particular should ask specifically about secondary dwelling approvals, since both states have had periods of tightened and loosened rules around granny flat rentals over the past decade, and older approvals may not reflect current requirements.