Section 4.15 in 2026: how councils assess significant likely impacts

Since 15 December 2025, section 4.15(1)(b) of the Environmental Planning and Assessment Act 1979 asks a NSW council to consider the significant likely impacts of a development, not every likely impact. A planner in Blacktown, Parramatta or Newcastle still works through the same five heads, but section 4.17(1)(a1) now confirms that conditions can deal with any likely impact, and section 65A of the EP&A Regulation 2021 takes the impacts of other development out of the impacts head. For home owners lodging a house, duplex or townhouse DA, the Statement of Environmental Effects (SEE) should now separate significant impacts from minor ones that conditions can manage.

Who this is for: home owners lodging, or waiting on, a house, knock-down rebuild, duplex or small townhouse DA in NSW who want to know how the amended section 4.15 will be applied and what their SEE needs to show.

Updated guide. This guide replaces our earlier article Section 4.15 matters: how a council planner actually assesses your DA, which reflects the law before the Planning System Reforms Act 2025 commenced.

What changed in section 4.15 on 15 December 2025?

The Environmental Planning and Assessment Amendment (Planning System Reforms) Act 2025 received assent on 24 November 2025 and is commencing in stages. The first stage made these changes to DA assessment. The Department has also published a Section 4.15 Practice Note on the amended section.

Heads (a), (c), (d) and (e) are unchanged: the planning instruments and DCP, site suitability, submissions and the public interest. At the first commencement, section 65A was the only provision made under the new section 4.15(1A) power. More may follow, so check the current Regulation.

What does “significant” change for a house, duplex or townhouse DA?

Less than some commentary suggests. The planner still looks at overshadowing, privacy, views, bulk and scale, stormwater, tree loss, traffic and construction effects. Most of those are also DCP controls, and head (a) still requires the DCP to be considered, so a solar access or setback shortfall still has to be addressed.

What changes is the weight. The amended head sets no numeric thresholds, so whether an impact is significant remains planning judgement on the facts of the site, guided by the Practice Note. As a rough guide:

• Likely to be significant: a first floor living room window looking into a neighbour’s private open space at close range, or a wall that removes most of the midwinter sun from an adjoining living area.
• Likely to be minor: a short period of extra shadow over a side passage, or a highlight bathroom window facing a blank wall.

We would not say minor impacts can never matter. Several small impacts on one neighbour can add up, a DCP departure still needs a merit justification, and councils will apply the new wording differently while practice settles. The risk now is the opposite of the old mistake: lodging a thinner SEE on the assumption that council no longer looks at amenity. It does, and shadow diagrams and privacy analysis are how the planner decides whether an impact is significant in the first place.

How do conditions deal with impacts that are not significant?

Section 4.17(1)(a1) allows a condition if it relates to a likely impact of the development; the word “significant” is not in it. Read with the amended head (b), the structure points to real but minor impacts being managed by conditions rather than becoming a reason to refuse. Typical examples are privacy screens or obscured glazing, boundary landscaping, tree protection under AS 4970-2009, sediment control, construction hours and detailed stormwater design at construction certificate stage.

So the SEE can propose the condition that resolves each minor impact, giving the planner an answer instead of a reason for an information request. The limit is head (c). An unresolved flood constraint, no lawful stormwater discharge point or an inadequate bushfire assessment goes to whether the land can carry the development at all, and a condition cannot fix that.

Why does section 65A matter if the block next door is also being developed?

Section 65A says the impacts of other development not included in the DA are not relevant when assessing the significant likely impacts of your development. Your application is judged on the impacts it causes, not on those of a separate proposal on the adjoining lot.

Two cautions. It applies to head (b) only, not to site suitability or the public interest. And its exact reach, for instance in arguments about cumulative change in a street, will be worked out through council practice and possibly the Land and Environment Court. The existing neighbouring dwellings remain the setting against which your impacts are measured.

Is a DA lodged before 15 December 2025 still assessed under the old rules?

Only for 12 months. To work out where yours sits:

1. Find the formal lodgement date on the NSW Planning Portal. An application submitted but not yet accepted as lodged on 15 December 2025 falls under the new provisions.
2. If it was lodged before 15 December 2025 and is determined by 15 December 2026, the old wording applies. The same saving covers modification applications.
3. If it is still undetermined after 15 December 2026, it is assessed under the new provisions, including section 65A.
4. The new objects of the Act do not apply to a DA or modification lodged before 15 December 2025.
5. Consider whether documents need updating. The Department’s view is that in most cases they will not, but it is case by case.

For long-running DAs, note that since 21 March 2026 the right to appeal a deemed refusal continues until the application is determined. The deemed refusal periods are unchanged: 40 days for most local development and 60 days for integrated development or where concurrence is required, excluding stop-the-clock periods.

Do DCP controls still matter, and what about clause 4.6?

Yes. Section 4.15(3A) still directs the consent authority to apply DCP provisions flexibly and accept reasonable alternative solutions that achieve a control’s objectives. A side setback slightly under the DCP figure can be approved where the SEE shows the objective (privacy, amenity, streetscape) is still met.

Section 4.15(3A) does not apply to LEP development standards such as height, floor space ratio or minimum lot size. A breach of those still needs a written request under clause 4.6, which is why a clause 4.6 variation request often sits alongside the SEE.

How are modifications and targeted assessment development handled?

For modifications lodged from 21 March 2026 under section 4.55(1A), 4.55(2) or 4.56, the section 4.15(1) matters are considered only to the extent relevant to the modification. Changes with no environmental impact moved to section 4.55(1), with a 14-day determination period and the deemed approval mechanism in section 4.55A. Our DA modifications service covers pathway choice.

The same date commenced targeted assessment development. Section 4.15(1C) and (1D) limit the matters considered for development a SEPP has declared eligible, after a 28-day exhibition. It sits between complying development and a full DA and excludes complex projects and designated development. Nothing had been declared at commencement, so check for any later declaration before assuming it applies.

Who decides the DA once it has been assessed?

Most residential DAs are determined by council staff under delegation. Some go to a local planning panel under the state panel directions, for example because of the number of objections or the size of a departure from a development standard; your council can confirm the triggers.

The reforms are moving NSW to a model where every DA is decided by council staff or a local planning panel. From 16 January 2026, new regionally significant development applications, and most pending ones, go to the local planning panel where one exists, with limited exceptions for older applications. Where there is no local planning panel, regional planning panels continue for now. If staff refuse your DA, you have six months to seek a Division 8.2 review and can elect to have the local planning panel decide it, where one is constituted.

Definitions

Significant likely impacts

The wording of section 4.15(1)(b) since 15 December 2025, covering environmental, social and economic impacts that are significant.

Section 65A

A provision of the EP&A Regulation 2021 making the impacts of other development not in the DA irrelevant to head (b).

Condition of consent

A requirement attached to an approval. Under section 4.17(1)(a1) it may relate to any likely impact of the development.

Section 4.15(3A)

The provision requiring DCP controls to be applied flexibly where an alternative achieves the control’s objectives.

Targeted assessment development

Development declared in a SEPP for a narrower assessment under section 4.15(1C) and (1D).

Our planners write every Statement of Environmental Effects to the section 4.15 structure, setting out which impacts are significant, which are minor and the conditions that would manage them. Anywhere in Sydney or regional NSW, send us the plans and we will provide a fee proposal.