Granny Flat Rules by State: Government Approval Paths (2026)

“Granny flat” is an everyday label, not one national approval category. Planning systems use terms such as secondary dwelling, small second home, ancillary dwelling, ancillary accommodation, secondary residence and independent unit. The applicable definition, approval path and rental conditions depend on the property's jurisdiction, zone, overlays, existing approvals and proposed design.

Official approval map by jurisdiction

These are starting points, not approvals for a particular address:

• New South Wales: the NSW Planning secondary-dwellings page says a proposal may be approved with development consent or as complying development if it satisfies the Housing SEPP and Codes SEPP. A lot must be at least 450 m² for the state complying-development path, but other standards and exclusions still need to be checked. A secondary dwelling approved under these provisions cannot be separately subdivided.
• Victoria: the Victorian Government's small second homes guide defines this pathway as a dwelling of 60 m² or less on the same lot as an existing home. It says a planning permit is not required in a residential zone on a lot of at least 300 m² if the specified requirements are met; overlays and other zones can change the answer. A building permit is always required, and the small second home cannot be separately subdivided.
• Queensland: the Queensland Planning guide says new secondary dwellings require building approval and owners must ask the local council whether development approval is required. State changes allow secondary dwellings to be rented to anyone, but an existing approval with an occupancy condition may require a change application.
• Western Australia: use the current Residential Design Codes. The WA Government says ancillary dwellings may now be proposed on all residential-zoned land, including grouped and multiple dwellings and strata lots. The applicable R-Code part, local planning framework and building approval still need an address-specific check.
• South Australia: PlanSA's ancillary accommodation FAQ says construction requires planning and building approval. It also says state rules do not restrict who may occupy ancillary accommodation. The proposal must remain secondary to the dwelling on the same allotment.
• Tasmania: use the official PlanBuild enquiry for the property and proposed work, then confirm the result with the council or a qualified planner. Do not import a floor-area or permit rule from another state.
• Australian Capital Territory: the ACT's secondary-residence application guide starts with the Territory Plan, zone, district policy and the proposal's assessment pathway. The ACT Planning Authority also says a leased block containing a primary dwelling and secondary residence cannot be subdivided under the cited ACT legislation.
• Northern Territory: NT.GOV.AU's independent-unit guide says building approval is required. Planning approval may not be required where every NT Planning Scheme requirement is met, but must be obtained where it is required; occupancy certification also applies in the circumstances described by the guide.

The property-specific check

Give the council, planner or certifier a defined proposal and ask them to confirm:

• the legal description, zone, overlays and controls applying to the land;
• whether the use fits the jurisdiction's definition of a secondary or ancillary dwelling;
• the planning assessment path and the separate building-approval path;
• site coverage, floor area, height, setbacks, access, parking, private open space and tree controls;
• bushfire, flood, heritage, contamination, easement and servicing constraints;
• wastewater, stormwater, electricity, water, metering and fire-separation requirements;
• whether a strata, community-title, lease or covenant approval is also needed;
• what certificate is required before lawful occupation.

The absence of a planning permit requirement does not mean there is no building permit, code, title or infrastructure requirement.

Existing or converted buildings

A shed, garage, studio or older backyard building is not automatically approved as a dwelling. Ask the authority to retrieve the approved plans, permits and occupation documentation, then compare them with the building as it stands. A change of use or conversion may require work for structure, fire safety, sanitation, light, ventilation, energy efficiency and access.

Before buying a property marketed as having a granny flat, make the contract review and building-file search address both the structure and its authorised use. Rental history does not prove planning or building compliance.

Renting the dwelling

Confirm rental permission through the law and approval applying to the address. Then identify the correct residential-tenancy agreement, minimum standards, bond process, smoke-alarm duties, insurance cover and utility arrangement. Short-stay accommodation may be a different use with separate registration or planning controls.

Queensland and Victoria now expressly permit the rental of qualifying secondary dwellings to people who are not relatives, and South Australia's official guidance removes an occupant relationship restriction. Those reforms do not establish the position for another jurisdiction or cure an unlawful building.

Rental tax and CGT

The ATO's residential rental property guidance requires rental income to be declared and limits deductions to eligible expenses for periods the property is rented or genuinely available for rent. Private use, below-market family arrangements and shared costs can require apportionment.

The ATO's main-residence guidance explains that using part of a home to produce income can affect the CGT exemption on a later sale. Keep records of construction, approvals, dates, rental use, income and expenses, and obtain registered tax-agent advice before relying on a projected after-tax return.

A granny flat interest is different

In tax and social-security law, a “granny flat interest” can mean a lifetime accommodation right. It is not simply the backyard building. Services Australia's granny flat interest guide says the arrangement can affect payment eligibility or rate and the assets test, and recommends legal and financial advice.

The targeted CGT exception described in the ATO's explanatory material concerns certain written, non-commercial lifetime accommodation arrangements for an eligible older person or person with disability. It is not a blanket CGT exemption for constructing or renting a granny flat.

Cost and value evidence

There is no defensible national build-cost, rent, yield or value-uplift figure. Obtain a site-specific scope, multiple comparable written quotes, servicing estimates and an independent rental appraisal. Ask a licensed valuer to assess the whole property if the decision depends on resale value or finance. Calculate return on the total incremental cash committed, not construction cost alone.

For general construction due diligence, see the building a new home guide.

General information only, not planning, building, legal, tax, valuation or financial advice. Reviewed 24 August 2026. Controls change and property-specific overlays or approvals can alter the result. Confirm the current position with the responsible authority and qualified advisers before committing money.