What our analysis shows
Our calculations, data as of 23 October 2026
- A standard 60 m² two-bedroom flat comes to $187,000 turnkey in Adelaide ($164,500–$209,500), the lowest of the capital cities in our model, and $159,500 in regional SA. Building to the 70 m² maximum takes it to $212,500.
- Eastern Adelaide gives the best payback in the state, 9.5 years, on a median two-bedroom house rent of $628. Northern Adelaide is the weakest metro region at 12.0 years.
- South Australia ties the land tax exemption to floor area. RevenueSA gives a full home exemption only if at least 75% of the floor area of all buildings, sheds and garages included, is the owner's home. By our reading, a rented flat over a quarter of the total costs you part of the exemption. A 60 m² flat needs at least 180 m² of house, garage and sheds beside it; a 70 m² flat, 210 m².
- SA's one-bedroom "house" bond median is about $290 in every Adelaide region, against $474 for a one-bedroom flat. That category seems to hold rooms and old cottages rather than new granny flats, so we used flat rents for one bedroom.
Fastest payback in South Australia, 60 m² two-bedroom flat
- Eastern Adelaide9.5 years
- Western Adelaide10.2 years
- Adelaide metro10.6 years
- Southern Adelaide10.9 years
- Northern Adelaide12.0 years
- Regional SA13.7 years
After agent fees, insurance, maintenance and tax at 30%, no loan. Rents: SA Housing Trust private rental report, new bonds April–June 2026.
What you pay for
| Line, 60 m² in Adelaide | Cost |
|---|---|
| Construction | $153,000 |
| Site preparation (flat, easy access) | $12,000 |
| Sewer, water, power and stormwater connections | $10,000 |
| Design, engineering and NatHERS energy rating | $8,000 |
| Approval: Deemed-to-satisfy planning and building consent | $4,000 |
| Total | $187,000 |
| Size | Budget | Standard | Premium | Standard, regional |
|---|---|---|---|---|
| Studio, 35 m² | $113,400 | $131,300 | $160,500 | $113,800 |
| 1 bed, 45 m² | $130,500 | $152,200 | $187,700 | $130,900 |
| 2 bed, 60 m² | $159,000 | $187,000 | $232,900 | $159,500 |
| 2 bed, 70 m² | $179,800 | $212,500 | $266,100 | $180,400 |
Rents by region
| Area | 1-bed rent | 2-bed rent | 60 m² build | Net yield |
|---|---|---|---|---|
| Eastern Adelaide | $495 | $628 | $187,000 | 14.2% |
| Western Adelaide | $390 | $585 | $187,000 | 13.1% |
| Adelaide metro | $474 | $563 | $187,000 | 12.6% |
| Southern Adelaide | $398 | $550 | $187,000 | 12.3% |
| Northern Adelaide | $360 | $500 | $187,000 | 11.0% |
| Regional SA | $260 | $380 | $159,500 | 9.5% |
The two-bedroom figures are house rents, which run $40 a week above two-bedroom flats across Adelaide. A detached granny flat with outdoor space sits between the two, so treat these as an upper figure. The one-bedroom figures are flat rents.
Rent data: SA private rental report data, April–June 2026.
The 75% floor-area test
RevenueSA's land tax guide sets three conditions for the full home exemption. The third: at least 75% of the total floor area of all buildings on the land, including sheds and garages, is used as the owner's principal place of residence. A tenanted granny flat is not part of your residence, so its floor area counts against the 75%. Where 25–75% of the floor area is used for a business or commercial purpose, a partial exemption applies on a sliding scale.
| Granny flat | House, garage and sheds | Flat's share | Exemption |
|---|---|---|---|
| 45 m² | 150 m² | 23% | Full |
| 60 m² | 150 m² | 29% | Partial: 75% of value exempt |
| 60 m² | 200 m² | 23% | Full |
| 70 m² | 180 m² | 28% | Partial: 75% of value exempt |
| 70 m² | 240 m² | 23% | Full |
Partial exemption matters only if your land's taxable value is above the land tax threshold, and the guide frames the scale around business use. How RevenueSA treats a family member living rent-free is not addressed in the guide. If your flat is near the 25% line, ask RevenueSA before you build. Counting the garage and garden shed in the total is the easiest way to stay under it. The full rule is in RevenueSA's guide.
Approval and timing
Every SA granny flat needs planning consent and building consent before work starts. A design that meets the deemed-to-satisfy standards is decided within five business days of the planning documents being accepted, but with document checks and building consent most owners should allow four to eight weeks in total. Our model allows $4,000 for both consents. A design that misses a standard is performance assessed, which takes 20 to 70 business days depending on referrals and neighbour notification.
The flat can have its own outdoor area, and builder guides commonly plan about 20 m² for it. The 2024 Code amendment also requires the main dwelling's private open space to be accessible to all occupiers, so the flat's tenants cannot be fenced out of the main garden entirely. Some builder guides cite a minimum site area for the deemed-to-satisfy route; the Planning and Design Code varies by zone, so check your zone's policies before you buy a block for a flat.
Other SA checks
In Greater Adelaide, SA Water charges an augmentation fee when the flat gets its own water or sewer connection; sharing the main house's connection avoids it. Off-sewer blocks in the Adelaide Hills and rural areas need an aerobic wastewater system, typically $8,000–14,000 plus an annual service contract. Much of Adelaide's north and north-east sits on reactive clay that needs engineered footings, so get the soil report before accepting a fixed price. The builder must be licensed with Consumer and Business Services and hold building indemnity insurance for domestic work above the statutory threshold.
This week's worked example
Week of 19 October 2026. A new example, rule and owner report every Monday.
A 60 m² two-bedroom flat with a premium finish on a steep block, services 30 m from the house, in Adelaide metro: our model puts it at $272,200 turnkey ($239,500–$305,000), or $4,540 per m². At the area's median 2-bedroom bond rent of $563 a week it would return 8.4% net and pay back in 15.3 years after tax.
Rule check: South Australia's ancillary accommodation can be fully self-contained, up to 70 m² and two bedrooms; the change started on an interim basis on 29 February 2024 and was adopted on 18 November 2024.
From an owner (Australia, 2018): Renters noted that older flats tend to include utilities in the rent while newer ones are separately metered.