What our analysis shows
Analysis by Granny Flat Numbers, data as of 23 October 2026
- A 45 m² one-bedroom flat costs $179,000 in Sydney. If the alternative is your parent renting a one-bedroom flat nearby at the bond median, the build equals about 4.8 years of that rent. Across our areas it ranges from 4.8 years (Greater Sydney) to 9.9 (Logan).
- Centrelink treats a parent who pays to build a granny flat on a child's land as having received fair value: paying for construction is not counted as gifting. Transferring other assets, or paying a lump sum for an existing flat, is tested against a "reasonable value" that falls steeply with age.
- By the government's conversion factors, a right to live in a flat is valued at 16.56 times the annual couple pension for a parent turning 71, but only 6.6 times at 86. Paying more than that for an existing flat counts as a gift.
- If the parent leaves within five years for a reason that could have been expected, such as a move into aged care, Centrelink reviews the arrangement and the gifting rules can apply. In the family threads we read, it came up only as an afterthought.
Years of a parent's rent that equal the cost of a 45 m² flat
- Greater Sydney (NSW)4.8 years
- Gold Coast (QLD)5.1 years
- Brisbane (QLD)5.3 years
- Hills and north-west (NSW)5.3 years
- City of Melbourne (VIC)5.4 years
- Eastern Adelaide (SA)5.9 years
- Western Sydney (NSW)5.9 years
- Adelaide metro (SA)6.2 years
Build: our model, standard finish. Rent avoided: median new-bond rent for a 1-bedroom flat in the same area.
Against renting nearby
The cleanest comparison for a family flat is what the parent would otherwise pay to live close by. We took the median bond rent for a one-bedroom flat in each area and divided the cost of building a 45 m² flat by a year's rent:
| Area | 45 m² flat | 1-bed rent nearby | Years of rent |
|---|---|---|---|
| Greater Sydney (NSW) | $179,000 | $719 / wk | 4.8 |
| Gold Coast (QLD) | $161,500 | $615 / wk | 5.1 |
| Brisbane (QLD) | $161,500 | $590 / wk | 5.3 |
| Hills and north-west (NSW) | $179,000 | $650 / wk | 5.3 |
| City of Melbourne (VIC) | $161,500 | $570 / wk | 5.4 |
| Eastern Adelaide (SA) | $152,000 | $495 / wk | 5.9 |
| Western Sydney (NSW) | $179,000 | $580 / wk | 5.9 |
| Adelaide metro (SA) | $152,000 | $474 / wk | 6.2 |
| Wollongong (NSW) | $154,000 | $480 / wk | 6.2 |
| Sunshine Coast (QLD) | $161,500 | $500 / wk | 6.2 |
| Monash (VIC) | $161,500 | $495 / wk | 6.3 |
| Cairns (QLD) | $139,000 | $420 / wk | 6.4 |
| Newcastle (NSW) | $154,000 | $450 / wk | 6.6 |
| Central Coast (NSW) | $154,000 | $430 / wk | 6.9 |
| Merri-bek (VIC) | $161,500 | $450 / wk | 6.9 |
| Whitehorse (VIC) | $161,500 | $450 / wk | 6.9 |
| Southern Adelaide (SA) | $152,000 | $398 / wk | 7.4 |
| Darebin (VIC) | $161,500 | $420 / wk | 7.4 |
| Wyndham (VIC) | $161,500 | $420 / wk | 7.4 |
| Launceston (TAS) | $135,000 | $350 / wk | 7.4 |
| Western Adelaide (SA) | $152,000 | $390 / wk | 7.5 |
| Rest of NSW (NSW) | $154,000 | $395 / wk | 7.5 |
| Toowoomba (QLD) | $139,000 | $350 / wk | 7.6 |
| Greater Bendigo (VIC) | $139,000 | $350 / wk | 7.6 |
| Greater Hobart (TAS) | $157,000 | $395 / wk | 7.6 |
| Knox (VIC) | $161,500 | $405 / wk | 7.7 |
| Redland (QLD) | $161,500 | $400 / wk | 7.8 |
| Greater Geelong (VIC) | $139,000 | $340 / wk | 7.9 |
| Frankston (VIC) | $161,500 | $385 / wk | 8.1 |
| Northern Adelaide (SA) | $152,000 | $360 / wk | 8.1 |
| South-west Sydney (NSW) | $179,000 | $420 / wk | 8.2 |
| Whittlesea (VIC) | $161,500 | $375 / wk | 8.3 |
| Townsville (QLD) | $139,000 | $320 / wk | 8.4 |
| Ipswich (QLD) | $161,500 | $370 / wk | 8.4 |
| North-west coast (TAS) | $135,000 | $300 / wk | 8.7 |
| Hume (VIC) | $161,500 | $350 / wk | 8.9 |
| Moreton Bay (QLD) | $161,500 | $340 / wk | 9.1 |
| Casey (VIC) | $161,500 | $340 / wk | 9.1 |
| Ballarat (VIC) | $139,000 | $288 / wk | 9.3 |
| Brimbank (VIC) | $161,500 | $330 / wk | 9.4 |
| Regional SA (SA) | $131,000 | $260 / wk | 9.7 |
| Logan (QLD) | $161,500 | $315 / wk | 9.9 |
In the dearest rental markets the flat equals about five years of rent, and it stays with the property afterwards. Where flats rent cheaply, the case rests on care and closeness rather than money.
Centrelink: the granny flat interest
A granny flat interest is a right to live in a home for life, created by paying money or transferring assets to the owner. Services Australia's current guidance says a parent is not treated as having paid more than the interest is worth when they pay to build a granny flat on someone else's property, transfer their home but keep a life right to live there or in another property, or buy a property in someone else's name with a life right.
The amount paid, the entry contribution, also decides homeowner status. If it is more than the gap between the non-homeowner and homeowner assets limits, the parent is assessed as a homeowner, the contribution is not counted as an asset, and Rent Assistance is not available. If it is less, they are a non-homeowner and the contribution is counted. Source: Services Australia: how we assess granny flat interests.
When other assets are transferred, or a lump sum is paid towards an existing flat, a reasonableness test applies. Financial planners use conversion factors that multiply the annual partnered pension rate by a factor based on age next birthday:
| Age next birthday | Conversion factor |
|---|---|
| 66 | 20.64 |
| 71 | 16.56 |
| 76 | 12.78 |
| 81 | 9.41 |
| 86 | 6.6 |
| 91 | 4.52 |
From the Department of Social Services' Social Security Guide 4.6.4.60, last reviewed 4 November 2024. For couples, the younger partner's age is used.
Anything paid above the reasonable value is a deprived asset (a gift) and counts against the pension for five years. The free Financial Information Service at Services Australia can run the numbers for your family before you commit.
The family agreement
A written agreement protects the parent, the owner and siblings. It should cover who paid what, the parent's right to live there for life, what happens if the property is sold (the right must be kept as a condition of sale, moved to another property, or bought out), who pays rates, insurance and repairs, and what happens if the parent moves into care. A written, binding, non-commercial agreement is also what qualifies for the capital gains tax exemption; see capital gains tax.
Families in the forum threads we read most often struggled with the siblings' share: a child funds the flat on a parent's land, and the estate later divides the property equally. Each side should get independent legal advice.
When things change
- Leaving within five years. Centrelink reviews the interest. If the reason could have been expected when it was created, such as declining health leading to aged care, gifting rules apply; sudden illness, family breakdown or elder abuse may be treated differently.
- Temporary absences of up to 12 months (two years after property damage) are allowed within the five years.
- After the parent. A flat built to rent later, with its own entry and meters, keeps its value to the family.
Designing for age
Step-free entry, a 1 m wide path from the street, a hob-free shower with grab-rail reinforcement in the walls, wider doors and a bedroom big enough for a carer's chair cost little at design stage. A second small bedroom lets a carer stay overnight; see one or two bedrooms.
This week's worked example
Week of 19 October 2026. A new example, rule and owner report every Monday.
A 65 m² two-bedroom flat with a standard finish on a block with some slope, services 20 m from the house, in Regional SA: our model puts it at $185,500 turnkey ($163,500–$208,000), or $2,860 per m². At the area's median 2-bedroom bond rent of $380 a week it would return 8.1% net and pay back in 15.8 years after tax.
Rule check: The May 2026 Budget proposed replacing the 50% CGT discount with cost-base indexation and a 30% minimum tax from 1 July 2027; the bill was before Parliament when we last checked.
From an owner (QLD, 2021): For a sister living rent-free in a flat on the owner's home, replies agreed there is no income tax or CGT effect; the CGT question arises only when rent is charged.
Questions people ask
Does building a granny flat affect my parents' pension?
It can. If your parent pays to build the flat on your land in return for a right to live there for life, Centrelink does not treat the payment as a gift, but it decides whether they are assessed as a homeowner. Transfers of other assets are tested for reasonableness, and leaving within five years triggers a review.
Do we need a written agreement for a granny flat for a parent?
It is strongly advised, and for the capital gains tax exemption on granny flat arrangements it is required: a written, binding, non-commercial agreement giving the parent a right to live there for life.
Can my parent rent the granny flat from me?
Yes. Rent is then income for you, with the usual tax, and may affect land tax and capital gains tax on your property. Many families instead use a granny flat interest, where the parent contributes to the build in return for a life right.