NSW s4.55 modifications: pick the right modification pathway
NSW s4.55 modifications: s4.55(1) clerical, s4.55(1A) minimal impact, s4.55(2) substantially same. Timeframes, fees, when to use each, builder gotchas.
Ask Chalkline about this →TL;DR
When a DA consent is already in hand but the design has shifted, you need a section 4.55 modification under the EP&A Act 1979 rather than a fresh DA. Three sub-sections apply to different sized changes: s4.55(1) for clerical errors, s4.55(1A) for minor changes with minimal environmental impact, and s4.55(2) for anything bigger that still results in “substantially the same development.” The “substantially the same” test in s4.55(2) is tighter than most builders expect. A significant footprint increase or an extra storey will likely fail it. If the change is too large for s4.55(2), the alternative is s4.56 (deferred commencement) or a fresh DA. Building mid-construction without approving the modification first is a breach of consent.
When you do this
A modification is the right pathway when:
- A DA consent exists and is active (not lapsed)
- The Construction Certificate has been issued and is active (a lapsed CC means the modification application cannot proceed)
- The proposed change is to the approved development, not a completely different proposal
- The change does not trigger the need for an entirely new development type
A modification is not a substitute for a fresh DA if the concept has fundamentally changed, the site has changed, or the original consent has lapsed. For works where the consent has lapsed, start again with a new DA.
The three sub-sections
| s4.55(1) | s4.55(1A) | s4.55(2) | |
|---|---|---|---|
| Scope | Minor error, misdescription, or clerical mistake in the consent | Modification of minimal environmental impact | Modification resulting in substantially the same development |
| Notification | None required | Limited (council discretion, typically 14 days to affected neighbours) | Full re-notification: 14 days minimum, same as original DA |
| Timeframe | 4 to 6 weeks | 8 to 12 weeks | 12 to 20 weeks, longer if referrals triggered |
| Fee | Low, set by council (typically a flat admin fee) | Moderate (council sets, often 25 to 50% of original DA fee) | Typically 50% of the original DA fee; larger jobs proportionally higher |
| Council discretion | Narrow: only genuine errors | Moderate: council assesses impact | Full: council reassesses on merit |
| Commonly used for | Wrong lot number, typo in approved area, wrong plan sheet referenced | Small window relocation, minor setback change with no impact on neighbours | Room addition, garage conversion, facade redesign, footprint adjustment |
When to use which
s4.55(1): Use for genuine errors only. The consent says the garage is 5.4 m wide but the approved plans show 5.9 m and the dimensions add up to 5.9 m. That is a misdescription. Equally, wrong lot number, wrong property address, reference to a superseded plan sheet. Council will not stretch s4.55(1) to cover a design change dressed up as a clerical fix.
s4.55(1A): Use for small design changes where the impact on neighbours is negligible. The typical use case: a window moves 600 mm along a wall, a roof pitch changes by a degree or two, a materials substitution occurs (same profile, different colour). The change must be genuinely minor. If it affects privacy, overshadowing, or view corridors for adjoining owners, it probably belongs in s4.55(2) or needs to be redesigned.
s4.55(2): Use for anything larger that passes the “substantially the same” test. Adding a room, converting an internal garage to a bedroom, changing the facade treatment, adjusting the FSR compliance, or relocating the entry. The test is whether the modified development is still substantially the same as what was originally approved, assessed on the overall character and nature of the development. s4.55(2) is not a free pass: council reassesses the modification against the LEP, DCP, any applicable SEPPs, and public submissions.
The “substantially the same” test
“Substantially the same development” is not defined in the Act; it is a matter of planning judgment decided case by case. The Land and Environment Court has addressed it numerous times. Key factors:
- Footprint and bulk: A significant increase in gross floor area or site coverage is the most common reason a s4.55(2) application fails the test. Courts have found increases of 20% or more in floor area to be outside “substantially the same.”
- Number of dwellings: Adding a secondary dwelling or splitting a single dwelling into two changes the nature of the development, not just its character. Almost always outside s4.55(2).
- Height: An additional storey generally fails the test.
- Character: A change from a contemporary facade to a heritage-style facade, or vice versa, may still be substantially the same if the bulk and layout are unchanged.
- The whole, not the parts: Assess the modified development against the original consent holistically, not change by change.
If the test is not met, the options are s4.56 (see below) or a fresh DA.
The s4.56 alternative pathway
Section 4.56 of the EP&A Act 1979 allows the consent authority to modify a consent where the modification is not “substantially the same development.” This pathway is less commonly used and carries important conditions:
- The application is assessed on merit, the same way as a fresh DA
- Full notification and referral requirements apply
- The applicant must demonstrate why modification rather than a fresh DA is appropriate
- The original consent remains in effect during the assessment
In practice, if the change is large enough to fail the s4.55(2) test, most practitioners lodge a fresh DA rather than attempt s4.56. The procedural burden is similar and a fresh DA gives a cleaner slate for conditions of consent.
Documents needed
| Document | Notes |
|---|---|
| Covering letter | Identify which sub-section applies and why, describe the modification clearly |
| Modified architectural drawings | Clearly marked to show what has changed (cloud and delta system preferred) |
| Statement of reasons | Required for s4.55(1A) and s4.55(2); explains why the modification is appropriate |
| Updated BASIX certificate | Required if the modification affects thermal or water performance (e.g., window area changes, additional area) |
| Specialist reports | Any new or updated reports triggered by the change (shadow, heritage, flood, privacy) |
| Owner’s consent | If the applicant is not the registered owner |
| Fees | Council fee schedule; confirm with the council before lodging |
Lodge via the NSW Planning Portal in the same way as the original DA. Attach the original DA number and consent reference.
What can go wrong
| Issue | What happens | How to avoid it |
|---|---|---|
| Modifying mid-construction without approval | Breach of consent conditions. Stop-work order, potential enforcement action, OC refused | Get the modification approved before varying the work on site |
| Wrong sub-section used | Council rejects or reclassifies at their cost; delay and possible re-notification | Get a pre-lodgement check with council before preparing documents |
| Lapsed consent | Council cannot assess a modification application; must lodge a fresh DA | Watch consent expiry dates; renew before lapsing if possible |
| ”Substantially the same” test fails | Application refused; no fallback except s4.56 or fresh DA | Test the proposal against court precedents before lodging; redesign to stay within the original footprint or character if in doubt |
| Referral triggered by the modification | Timeframe blows out (RFS, Sydney Water, Heritage NSW can add weeks) | Check overlays before lodging; assume the referral will apply |
| Conditions not read before modifying | Modification conflicts with a condition of consent that was missed | Read the conditions of consent before any design change; flag conflicts early |
How to use this with related articles
Start with the DA process NSW article to understand how the original consent was granted and what conditions apply. Before lodging a modification, read conditions of consent: how to read them to confirm the modification does not create a conflict with an existing condition. If the original DA went through a notification process, DA exhibition and notification rules NSW explains what your modification re-notification will involve.
References
-
Environmental Planning and Assessment Act 1979 (NSW), legislation.nsw.gov.au. Sections 4.55 (modification of consents) and 4.56 (modification involving substantially different development). Verified 2026-05-23.
-
Modifying a development consent, Department of Planning, Housing and Infrastructure. Guidance on the modification pathways under the EP&A Act. Verified 2026-05-23.
Related
- DA process NSW: how the original consent was granted
- Conditions of consent: how to read them: know what you are modifying before you start
- DA exhibition and notification rules NSW: what re-notification looks like in practice
- Planning instrument hierarchy AU: where the EP&A Act sits in the planning stack
See also
- CDC NSW: complying development as an alternative to the DA/modification path
- Land and Environment Court appeals NSW: appeal options if a modification is refused
- LEPs NSW: the Local Environmental Plans that govern merit assessment
- DCPs: Development Control Plans assessed in s4.55(2) applications
- DCP (glossary)
- LEP (glossary)
Last updated: 2026-05-23. Verified: 2026-05-23. Quarterly review for currency.