What Is a BASIX Certificate? NSW Requirements & Cost (2026)
A BASIX certificate (Building Sustainability Index) is the NSW planning document that proves your new home or renovation meets state targets for energy, water, and thermal comfort. Most BASIX reports cost $80–$300 and are issued in 2–5 business days by an accredited BASIX consultant — usually bundled with a NatHERS assessment. Below: when you need one, who can issue it, and how to get yours.
The three BASIX targets
Thermal Comfort
Usually satisfied via a 7-star NatHERS rating. Measures heating/cooling loads against climate-zone-specific caps.
Energy
Scored on hot water system, heating/cooling choice, lighting, cooktop, pool pump, and solar PV.
Water
Rainwater tank, dual-flush toilets, water-efficient taps and showerheads, drought-tolerant landscaping.
BASIX certificate cost (2026)
| Project type | Lodgement fee | Consultant fee | Total |
|---|---|---|---|
| DIY single dwelling | $80–$140 | $0 | $80–$140 |
| Consultant — single dwelling | $80–$140 | $150–$300 | $230–$440 |
| Bundled with NatHERS (new build) | Included | Included | $450–$900 |
| Multi-unit (per dwelling) | $50–$100 | $80–$200 | $130–$300 |
Most NSW homeowners bundle BASIX with a NatHERS assessment — the same assessor handles both, which is usually cheaper than buying them separately.
When you need a BASIX certificate
- All new residential builds in NSW (houses, units, townhouses)
- Alterations or additions with an estimated cost over $50,000
- Swimming pools or spas with a capacity over 40,000 litres
- Knockdown-rebuilds and dual occupancies
Outside NSW? Other states use their own equivalents — see our disclosure requirements checker.
BASIX requirements explained (2026)
BASIX requirements are set by the NSW Government and vary by dwelling type, location and climate zone. Every residential project has to pass all three targets below — a fail on any one target means the certificate won't generate, and your DA or CDC can't be lodged.
| Target | What's measured | Typical pass mark | Most common fix |
|---|---|---|---|
| Thermal comfort | Heating and cooling loads against climate-zone caps | 7-star NatHERS (new homes) | Better glazing, added insulation, eaves/shading |
| Energy | Hot water, heating/cooling, lighting, cooktop, pool pump, solar PV | Score varies by dwelling type and postcode | Heat pump hot water, reverse-cycle A/C, rooftop solar |
| Water | Fixtures, rainwater tank, landscaping, pool cover | Commonly 40% reduction on benchmark | Rainwater tank connected to toilets and laundry |
What you need before you start
- Site address and lot/DP details, plus the estimated project cost
- Scaled architectural plans — floor plans, elevations, sections and a site plan
- Floor, wall, roof and window areas, and construction types with insulation R-values
- Glazing specifications (U-value and SHGC) from your window supplier
- Fixture, appliance, hot water, heating/cooling and solar PV selections
- Rainwater tank size and what it will be connected to, plus landscaped area
Which BASIX pathway applies to you
Single Dwelling
New houses, knockdown-rebuilds and dual occupancies. Thermal comfort via the DIY method or a NatHERS rating.
Multi Dwelling
Townhouses and apartment buildings. Each dwelling is assessed, and common areas are covered separately.
Alterations & Additions
Renovations over $50,000. Only the new and affected work is assessed, with lighter targets than a new build.
What's exempt
Work under the $50,000 threshold, internal-only fitouts with no change to services, repairs and maintenance, demolition-only applications, pools under 40,000 litres, and non-residential (Class 5–9) buildings — those fall under Section J of the NCC instead.
How to get a BASIX certificate, step by step
- 1Finalise your plans. BASIX runs off measured areas and specifications, so changes after the certificate is issued usually mean re-issuing it.
- 2Choose your thermal comfort path. The DIY method is quicker for simple homes; a NatHERS assessment gives more design freedom and is required for most 7-star new builds.
- 3Enter the project in the NSW Planning Portal. Dwelling details, construction, fixtures, appliances and landscaping all get scored as you go.
- 4Adjust until all three targets pass. If you're short, the cheapest levers are usually hot water system, glazing and rainwater tank size.
- 5Pay the lodgement fee and generate the certificate. It's issued instantly once payment clears.
- 6Lodge it with your DA or CDC and make sure the commitments shown on the certificate are carried through to construction — a certifier checks them at occupation.
Want a price first? See our BASIX certificate cost breakdown.
Get BASIX + NatHERS quotes from local NSW assessors
Most NSW assessors bundle BASIX and NatHERS together. Tell us your postcode and project — we'll match you with assessors who handle both.