Buying a Property With a Granny Flat

A secondary dwelling in the backyard, commonly called a granny flat, is one of the more common additions buyers encounter on an otherwise ordinary house purchase. It can be a genuine asset, offering rental income potential or space for extended family, but it also introduces a layer of due diligence that a standard single-dwelling residential purchase does not require. The building itself is rarely the issue. The question your conveyancer needs answered is whether the granny flat was properly approved, built in line with those approvals, and is being used in a way that complies with council and state planning rules.

Was It Actually Approved

Many granny flats are approved as complying development or under a fast-tracked secondary dwelling pathway, rather than through a full development application. This is a legitimate route, but it comes with conditions, commonly a requirement that the property be occupied by the property owner or a family member rather than rented out separately, or minimum lot size and setback rules. In states such as New South Wales, a secondary dwelling can often be approved this way without a full development application, provided the block meets minimum lot size and setback requirements, though the specific pathway and conditions differ from state to state. Some older or informally built granny flats were never approved at all. An unapproved structure is not automatically worthless, but it changes the picture considerably, since it may need to be removed, modified, or retrospectively approved before it can be relied on for rental income or added to a valuation.

Checking the Compliance Certificate

Beyond the initial approval, a completed granny flat should have a final compliance or occupation certificate confirming the building was finished in accordance with the approved plans and the National Construction Code. Your conveyancer or building inspector should request this certificate as part of the standard document check, alongside the usual searches. A missing certificate is a common and fixable oversight, but it needs to be chased up before exchange rather than discovered afterwards, since a lender may require it before approving finance on a property being valued with rental income from the second dwelling. The same document gets requested again if you later look at refinancing the property, so it is worth keeping a copy on file rather than needing to chase it down a second time.

Understanding Use Restrictions

Even a fully approved granny flat often comes with conditions on how it can be used. Some approvals restrict occupation to family members and prohibit renting the dwelling to an unrelated tenant on a separate lease, while others explicitly allow independent rental. If you are planning to buy the property specifically for the rental income the granny flat can generate, this distinction matters enormously and should be confirmed against the actual conditions of consent, not assumed from how the current owner happens to be using it.

Separate Services and Metering

Granny flats are sometimes fitted with their own electricity sub-metering, hot water, or even a separate water connection, particularly where they are intended to be rented independently. Checking how services are metered and billed matters if you intend to lease the dwelling separately, since retrofitting separate metering after settlement adds cost and complexity that is easy to underestimate. Where the block backs onto shared infrastructure or an easement for stormwater or sewer servicing the second dwelling, this should also show up in a proper title and easement search.

How It Affects Land Tax and Rates

A council may reassess rates once it becomes aware a property generates rental income from two dwellings, and depending on how the arrangement is structured, there can be flow-on implications for land tax treatment as well. If the granny flat is being used under a formal family granny flat arrangement rather than an arm's length tenancy, there are specific capital gains tax rules that can apply to creating or ending that arrangement, and the ATO's guidance on granny flat arrangements and CGT sets out the current eligibility criteria. This is general information rather than tax advice, and anyone relying on a granny flat arrangement for family living should speak with an accountant about their specific situation.

Buying With an Existing Tenant in the Granny Flat

Where the vendor already rents the granny flat out to an unrelated tenant, you are effectively inheriting a residential tenancy along with the property, and the usual rules about buying a tenanted property apply to that second dwelling just as they would to the main house. This means checking the lease terms, bond details and rent arrears before exchange, and understanding whether the tenancy can continue after settlement or needs to be dealt with as part of the sale. If the existing approval only permits family occupation, an unrelated tenant already in the granny flat is itself a sign the current use may not match what council actually approved, worth raising directly with the vendor's conveyancer.

Boundary Setbacks and Overlooking Rules

Secondary dwellings are also subject to their own setback, height and privacy rules, which are sometimes stricter than those for the main house given their proximity to neighbouring boundaries. Councils commonly limit window placement and balcony areas on a granny flat to reduce overlooking into an adjoining yard, and retrospective approval for a structure that breaches these rules can be difficult or impossible to obtain. If a survey shows the granny flat sitting closer to a boundary than current rules allow, it is worth confirming whether it was approved under older rules that still validly apply, since planning rules are not always applied retrospectively.

What to Ask For Before Exchange

Before committing to buy, ask the agent or vendor for the original development consent or complying development certificate, the final occupation certificate, and any correspondence with council about the granny flat's approved use. If any of these documents are missing, your conveyancer can request council records directly, though this takes time and is best started early rather than during a short cooling-off period. Comparing this against a property with a fully separate title, such as a duplex or dual-occupancy purchase, highlights the difference: a granny flat almost always sits on the one title as the main house, so its legal status depends entirely on council approval documents rather than a separate certificate of title.

Getting this right protects both your finance approval and your ability to use the second dwelling the way you intend, whether that is extra rental income, space for family, or simply a home office separate from the main house.