Granny flats and tax: the 2021 reform that changed family housing arrangements

For Australian families where ageing parents are moving in with — or next door to — adult children, the granny flat conversation has several dimensions. The Centrelink and social security framework is one: the granny flat interest rules under the DSS Social Security Guide, the reasonableness test, and the assets test implications. But there is a distinct tax and estate planning dimension that is just as important and more often missed. Three elements stand out: a 2021 legislative reform that changed the CGT treatment of formal granny flat arrangements; a main residence exemption trap that affects the adult child's property; and a set of estate planning risks that are structural rather than regulatory.

What was the pre-2021 CGT position?

Before 1 July 2021, families formalising granny flat arrangements faced a technical CGT exposure that most were unaware of. The ATO's view was that creating a right of residence for life was a CGT event — the adult child was disposing of a partial interest in the property, and the parent was acquiring an asset. Varying the arrangement (adjusting terms as circumstances changed) could trigger a further CGT event. Terminating it when the parent moved to aged care or died was also potentially a CGT event. In practice, the amounts were often modest compared to the whole-property gain, but the compliance exposure was real — valuations were theoretically required, events needed to be reported, and the informal nature of most family arrangements meant the technical requirements were routinely ignored.

What did the 2021 reform change?

The Treasury Laws Amendment (2021 Measures No. 1) Act 2021 introduced a specific CGT exemption for granny flat arrangements, operative from 1 July 2021. The provision — section 118-178 of the ITAA 1997 — provides that CGT does not apply to the creation, variation, or termination of a qualifying arrangement. To qualify, the arrangement must involve an eligible person (defined as a person of pension age or with a disability), must be documented in a formal written agreement setting out the terms of the right of residence, and must be provided by a family member or related party for a property intended to be the eligible person's principal home. The effect: families using a written agreement get full CGT protection for the life of the arrangement — from the day it is entered to the day it ends. The old compliance exposure is gone for qualifying arrangements.

Why does the written agreement matter so much?

The critical condition: the written agreement. The reform does not protect informal arrangements. A parent moving into a granny flat with a handshake understanding does not qualify. The written agreement requirement is not merely procedural — it is the condition that triggers the exemption. For families who enter into these arrangements without documentation (which historically was the majority), the pre-2021 CGT exposure may still apply for arrangements entered before 1 July 2021, and the new exemption will not apply unless the arrangement is properly documented. There is a practical case — both for CGT protection and for clarity about the parties' intentions — for formalising the arrangement through a solicitor.

What does the CGT exemption not cover?

Section 118-178 exempts the arrangement itself — the right of residence. It does not exempt the underlying property from CGT when it is eventually sold. And it does not cover stamp duty: any transfer of land title in connection with the arrangement (for example, a parent transferring their home to an adult child in exchange for a right of residence elsewhere) is still subject to state and territory stamp duty, which varies by jurisdiction and can be a material cost. The federal CGT exemption and the state stamp duty position are entirely separate.

What is the main residence trap?

For the adult child who owns the property, the main residence exemption (subdivision 118-B ITAA 1997) is at stake. The exemption provides CGT relief for gains on a property that is the owner's principal home. Where a granny flat is built and used as a formal right of residence — with no rent paid — the property may continue to qualify fully for the main residence exemption on eventual sale, because no part of the dwelling is being used to produce income. But where the parent pays rent to the adult child, the picture changes. Any part of the home used to produce income triggers the partial-use rule (section 118-190 ITAA 1997). On eventual sale, a proportionate CGT gain applies to the rental portion — typically calculated by floor area — and that proportion does not receive the main residence exemption. The rental income creates a current-year tax liability (it is fully assessable) and a future CGT cost on sale. Families who choose a rental arrangement for Centrelink reasons — because the parent paying rent avoids the assets test implications of a formal granny flat interest transfer — should understand that the trade-off includes a permanent main residence exemption impact.

How is rental income treated for tax purposes?

Where the parent pays rent, that rent is assessable income to the adult child under ordinary income tax principles — there is no family relationship exemption. Deductible expenses (rates, insurance, mortgage interest, depreciation) can be claimed for the rental portion. Where rent is significantly below market rates, the ATO may limit deductions to the proportion that rent bears to market rent. Full deductibility requires market-rate rent; below-market family rents invite an apportionment challenge.

What estate planning risk do families miss?

A formal granny flat interest — a right of residence for life — is a personal right. It ends when the parent dies. It does not pass through the estate; the parent cannot bequeath it. More significantly, it may not bind the property if the adult child dies first. An unregistered right of residence is a personal obligation of the adult child; if the adult child dies before the parent and the property passes to another beneficiary or is sold, the parent may have no enforceable claim to remain. A registered life interest or caveat on the property title provides stronger protection — it travels with the property — but registration involves legal process and cost and may affect the adult child's ability to sell or mortgage the property. Families should have the arrangement reviewed by a solicitor who can advise on registration options, and the adult child's will should explicitly address what happens to the parent's right of residence if the adult child predeceases them. Where there are other children with expectations about the estate, the arrangement should be understood by all parties — transfer of a parent's assets to one child in exchange for a right of residence can affect the distribution expectations of other siblings.

What happens at the aged care transition?

When the parent eventually moves into residential aged care, the granny flat arrangement ends — the right of residence is no longer exercised. At that point, the parent's aged care funding depends on their remaining assets. Where the parent transferred substantial assets in exchange for the right of residence, those assets have passed to the adult child; they are not recoverable to fund the RAD (Refundable Accommodation Deposit) or DAP (Daily Accommodation Payment) in aged care. Pre-planning the aged care transition — including whether the parent retains enough independent assets to fund care without family assistance — is part of the arrangement design, not an afterthought.

What does a practical framework look like?

For families considering a granny flat arrangement, the conversation spans several disciplines: a financial adviser for the Centrelink and broader planning picture; a solicitor for the formal agreement, title registration, and estate planning; and an accountant for the CGT, income tax, and depreciation considerations. The 2021 reform has made formal written agreements both more protective and more necessary than before — the exemption only applies to documented arrangements. And the main residence, rental income, stamp duty, and estate planning questions sit alongside the Centrelink framework, not instead of it. A granny flat arrangement that is only partially planned is one where the undiscovered risks tend to surface at the worst possible time.

Sources

• ATO — Granny flat arrangements and CGT
• ATO — Using your home for rental or business
• ATO — Eligibility for main residence exemption
• DSS Social Security Guide — Granny flats: features, rights & interests (4.6.4.50)
• Services Australia — Granny flat interest
• My Aged Care — Understanding aged care home accommodation costs