DA vs CDC & BASIX

Before you build, you need approval — but there are two very different routes: a council-assessed Development Application (DA), or a fast, rules-based Complying Development Certificate (CDC) where the design fits the code exactly. And in NSW, residential work also triggers BASIX. Here is how to pick the path. (NSW terminology; VIC and QLD equivalents noted.)‍‌‌‌‌‌‌‌‌‌‌‌‌‌‌‌‍

DA vs CDC — two routes to approval

Development Application (DA): assessed on merit by the local council against the Local Environmental Plan (LEP) and Development Control Plan (DCP). It is flexible — you can negotiate height, setbacks and floor-space ratio — but it is slower (~8-20 weeks in NSW, longer with information requests or neighbour objections), and it separates planning consent (the DA) from construction approval (a Construction Certificate, CC), which you then get from a certifier.
Complying Development Certificate (CDC): a code-based, tick-the-box approval issued by an accredited (or council) certifier when the proposal meets the Complying Development Codes exactly — every numerical control satisfied "to the millimetre" under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008. It combines planning and construction in one step and is fast (~10-20 business days).

What fits CDC (NSW; VIC/QLD have their own code streams): new single dwellings on standard lots, compliant duplexes and some granny flats, minor extensions within the envelope and site coverage, internal alterations, garages, sheds and some pools. DA-only: anything exceeding the CDC envelope, heritage or environmentally sensitive land, much flood- or bushfire-prone land (CDC is often excluded), and unusual designs or significant streetscape changes. Any non-compliance with the code kicks you to the DA path.

BASIX (NSW)

The Building Sustainability Index is a NSW online assessment requiring a BASIX certificate for certain residential work — it forms part of the DA or CDC documents. It is required for:

new residential dwellings (houses, townhouses, apartments);
alterations and additions above a value threshold (commonly cited around $50,000 of works — confirm the current figure);
pools and spas over a volume threshold (commonly over 40,000 litres), even on an existing home.

It checks three things — energy (insulation, glazing, heating/cooling, hot water, lighting, possibly PV), water (fittings, rainwater, irrigation) and thermal comfort (orientation, glazing, shading, insulation) — by entering the data into the online tool. In NSW, BASIX is the mechanism that overlays the NCC energy provisions for residential work, so the certifier uses the BASIX certificate and specs to confirm both BASIX and NCC performance at the CC/CDC stage. (BASIX targets stepped up in late 2023 — confirm the current targets; see NCC Energy & NatHERS.)

Exempt development — no approval at all

The lowest tier is exempt development — very low-impact works that need neither a DA nor a CDC if they meet all the "exempt" standards (size, height, setbacks). In NSW these sit under the same SEPP 2008, with a per-item rule sheet on the Planning Portal:

small sheds and outbuildings under a max floor area and height, behind the building line and clear of boundaries and easements;
smaller carports meeting the size and setback rules;
modest, low, unroofed decks under the floor-area limits;
minor repairs (replacing windows, repainting).

Exceed any standard and you step up to CDC, then DA.

The other states

VIC: a planning permit where the scheme triggers it, plus a building permit; a fast code/VicSmart stream for compliant, non-contentious work (building-permit-only) versus a full planning permit (several months).
QLD: under the Planning Act 2016, development is accepted / code-assessable / impact-assessable — straightforward extensions in low-risk zones are often accepted or code-assessable (CDC-like, a few weeks), while impact-assessable work with public notification is DA-like (months).

The universal pattern: code-compliant is faster and cheaper; full merit assessment is slower and dearer.

Common mistakes

Designing just outside the CDC envelope and being forced onto the slow DA path.
Forgetting BASIX on a $50k+ reno or a big pool.
Assuming a shed/carport/deck is exempt without checking the size, height and setback rules.
Trying CDC on flood-, bushfire-prone or heritage land where it is excluded.

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