Granny Flats and Negative Gearing After July 2027: What Property Owners Need to Know

Granny flats are a uniquely Australian planning fixture secondary dwellings on existing residential lots, typically used to house family members or generate supplementary rental income. The 2027 negative-gearing reform treats granny flats restrictively: where the underlying property is not itself eligible for negative gearing, the granny flat does not "rescue" it. This article walks property owners through the rules, the scenarios where granny flats retain favourable treatment, and the planning decisions that matter.

The three granny flat scenarios

Owner decisions about adding granny flats fall into three distinct tax buckets after 1 July 2027:

1. The underlying property is grandfathered (owned at 12 May 2026): granny flat inherits grandfathered status
2. The underlying property is a post-2027 established acquisition: granny flat is locked into the same restrictions
3. The granny flat is part of a development that satisfies the supply-increase test: granny flat qualifies as new build

Granny flat on a grandfathered property

If you owned the underlying investment property at 7:30pm AEST on 12 May 2026 and later add a granny flat, the granny flat's rental income and expenses fall under the same grandfathered treatment as the original property. Losses can offset wage income; full negative gearing applies.

Practically, this means the construction interest, depreciation on the granny flat (capital works at 2.5% over 40 years for new construction), and operating costs all deduct against the combined rental income. If the combined property runs at a loss, the loss is immediately deductible against the owner's salary. This is the most favourable outcome.

Granny flat on a post-2027 established acquisition

If you buy an existing house with intent to add a granny flat after 1 July 2027, the analysis becomes harsher. The underlying property is established residential, acquired post-commencement. Negative gearing against wages is unavailable. The granny flat does not change this.

Both the original house and the granny flat together produce a single carry-forward residential loss bucket. Losses accumulate, deductible only against future residential property income including rent surpluses and the eventual capital gain.

For an investor considering this strategy specifically to "convert" an established acquisition into new build, the answer is clear: it does not work. The carve-out is targeted at supply increase, and a granny flat is explicitly identified as not satisfying the test.

Granny flat as part of a new-supply development

The narrow path where a granny flat retains favourable treatment is when it is part of a development that independently satisfies the supply-increase test. For example: an investor buys vacant land, builds a primary dwelling and a separately titled secondary dwelling simultaneously. Pre-count: 0. Post-count: 2. The supply test is satisfied for both, including the secondary dwelling.

Alternatively, a KDR project that demolishes one existing house and constructs one new house plus one new (separately titled) granny flat may qualify 1 → 2 satisfies the supply test. Critically, this requires that local planning treats the secondary dwelling as a separate dwelling for the supply count, not as an ancillary granny flat.

Planning decisions that matter

• Separate title: can the secondary dwelling be separately titled (Torrens or strata)? If yes, it likely counts as a dwelling for the supply test.
• Size and self-containment: larger, fully self-contained dwellings are more likely to count than small ancillary studios.
• Council classification: some councils classify identical structures differently a "secondary dwelling" in NSW under SEPP (Affordable Rental Housing) may carry different recognition to a "granny flat" under simpler local instruments.
• Separate utilities and access: independent utility connections and external access support the "separate dwelling" classification.

Depreciation and capital works

Regardless of negative-gearing eligibility, depreciation on a newly constructed granny flat continues to apply under existing tax law. Capital works deduction (Division 43) at 2.5% annually over 40 years for residential construction completed after 16 September 1987 flows through. Plant and equipment depreciation (Division 40) is limited to new items for existing investors but full for new builds.

The deduction itself is unchanged; what changes is how it is used. For a grandfathered property the deduction offsets wage income. For a post-2027 established acquisition with a granny flat, the deduction sits in the carry-forward bucket awaiting future residential income. The economic value depends on when, and whether, that income arises.