Few things on a development site stay exactly as they were drawn at lodgement. A geotechnical report comes back worse than expected and the basement has to shrink. A builder finds a cheaper façade system that changes the window pattern. A financier wants an extra apartment to lift the loan to cost ratio. A condition of consent turns out to be unworkable in the field. Every one of these is a mid-project decision a property developer in New South Wales has to make, and every one of them runs into the same question: can the approved development consent be modified, or does the change force a fresh Development Application (DA) and another full assessment cycle?
That question is governed by section 4.55 of the Environmental Planning and Assessment Act 1979 (NSW) (EP&A Act). It is one of the most frequently used and least well understood provisions in the NSW planning system, and as of 21 March 2026 the rules around it changed materially. This guide works through how section 4.55 operates for a developer after those reforms: the three modification pathways, the new fast lane for no-impact changes, the “same or substantially the same development” test that decides whether a modification is even available, the fees and timeframes that feed a feasibility, the grounds councils most often use to knock a modification back, and how the equivalent regimes work in the other states and territories. The framing throughout is the developer’s: what it costs, how long it takes, and what it does to a margin.
What section 4.55 is, and what changed in March 2026
Section 4.55 is the statutory mechanism for changing a development consent that has already been granted. It sits in the Environmental Planning and Assessment Act 1979 (NSW), and it is the provision a developer reaches for whenever an approved scheme needs to move. Older consents, contracts, and council templates still refer to a “section 96 modification” or a “section 96 application”, because section 4.55 was numbered section 96 until the 2017 renumbering of the EP&A Act. The terms describe the same thing. A “section 4.55 modification”, a “s4.55 mod”, a “section 96 modification” and a “modification application” all refer to an application to change an existing consent rather than to obtain a new one.
The framework was overhauled by the Environmental Planning and Assessment Amendment (Planning System Reforms) Act 2025 (NSW), the second tranche of which commenced on 21 March 2026 by proclamation. The NSW Department of Planning, Housing and Infrastructure has confirmed in its second proclamation guidance that the modification changes apply to modification applications lodged on or after 21 March 2026, regardless of when the original DA was approved. A modification lodged before that date is generally assessed under the old framework; a modification lodged after it falls under the new one. For a developer with a consent granted years ago, the date that matters is the date the modification is lodged, not the date the consent was issued.
The reforms matter because they reshaped the cheapest and fastest pathway. Under the old rules, section 4.55(1) was confined to correcting minor errors, misdescriptions and miscalculations, which made it almost useless for genuine design changes. Under the new rules, section 4.55(1) also captures any modification that has no environmental impact, and it now carries a 14-day deemed non-refusal clock. That single change moves a large category of modifications, the kind that change documents or details without changing what the development does to its surroundings, out of the slow, notified pathways and into a fast administrative one. Most of the competing commentary still online describes the pre-reform position. A developer relying on it could badly misjudge which pathway, fee, and timeframe applies. The Department’s practice note on section 4.55 modifications, updated in 2026, is the current authority and is the basis for much of what follows.
The threshold question: modify, or lodge a fresh Development Application
Before choosing a pathway, a developer has to clear a prior question: is the change even eligible to be a modification at all? Section 4.55 cannot be used to turn one development into a different one. The change must involve, in the language the courts have used for decades, “alteration without radical transformation”. If what is proposed would radically transform the approved development, it is not a modification, and a fresh DA is required no matter how the application is dressed up.
This is the single most consequential strategic call in the whole exercise, and it is a commercial call before it is a legal one. A modification keeps the existing consent alive, narrows the assessment to the change itself, attracts a smaller fee, and generally runs faster. A fresh DA reopens the entire scheme to assessment, exposes it to the current planning controls (which may have tightened since the original consent), restarts notification and submissions, and resets the program clock by what could be six to twelve months. Our guide to DA approval in Australia covers what a full application involves; the point here is that being pushed off the modification pathway and onto a new DA is rarely a minor administrative difference. It can be the event that breaks a feasibility.
Because the stakes are asymmetric, the modify-versus-fresh-DA decision is worth modelling, not guessing. The cost of the modification fee and a short assessment delay sits on one side; the cost of a fresh DA, a longer delay, holding costs over that period, and the risk of assessment against tightened controls sits on the other. Modelling both scenarios side by side, including the holding cost of the extra months, is exactly the kind of comparison Feasly’s feasibility modelling is built for, and it often shows that paying a planner to make the strongest possible “substantially the same” case is cheap insurance against being forced down the fresh-DA road.
A developer also needs standing to lodge the modification. Only a person entitled to act on the consent may apply to modify it, which generally means the applicant for the original consent, the owner of the land, or a person with the owner’s authority. On a site that has changed hands since the original approval, the current owner steps into that role, but the consent and the right to modify it run with the land, not with the original applicant.
The three modification pathways
Section 4.55 sets up a tiered system. The pathway is determined by the environmental impact of the change, not by how big the change looks on paper. A developer who understands which tier a proposed change sits in can predict the fee, the notification requirement, the assessment timeframe, and the likelihood of objection before lodging anything.
Section 4.55(1): minor error or no environmental impact (the fast lane)
Section 4.55(1) is the streamlined pathway, and the 2026 reforms widened it considerably. It now covers two kinds of change. The first is the traditional one: correcting a minor error, misdescription or miscalculation, such as a typographical mistake, an incorrect reference to a plan or document, or an arithmetic or drafting error in a condition. The second, and the genuinely new category, is any modification that the consent authority is satisfied will have no environmental impact.
The Department’s practice note is precise about what “no environmental impact” means, and the precision matters. It is a threshold test, not a balancing exercise. The modification must not introduce any new negative environmental impact, including any increase to the severity or the distribution of an existing impact. If a change reduces impact in one respect but shifts or introduces impact in another, it fails the threshold even though it might be an improvement overall. In deciding whether a change has no environmental impact, a consent authority is directed to consider whether any element of the environment could be affected (amenity, air quality, biodiversity, Aboriginal cultural heritage, water, soils, environmental heritage, and economic and social factors), whether the change could affect elements not previously assessed, whether the location, extent, intensity or distribution of impacts would change even if overall impacts fall, and whether any additional environmental assessment would be needed to understand the change. If the honest answer to those questions is that some assessment would be required, the change is unlikely to qualify for section 4.55(1).
The reward for fitting within section 4.55(1) is speed. The new section 4.55A introduces a deemed non-refusal framework: the consent authority must determine a section 4.55(1) application within the period prescribed by the regulations, which is 14 days after lodgement. If it does not determine the application within that period, it must do so as soon as practicable afterwards and it must not refuse it. The authority can still impose conditions, but where conditions are imposed after the 14-day period has expired, they must relate only to the modification and must not defeat the purpose of the modification sought. In practical terms, a properly categorised no-impact modification now has a strong statutory tailwind: the council cannot sit on it indefinitely, and it cannot use the modification as an opening to reopen settled parts of the consent. One carve-out applies: the deemed non-refusal framework does not apply to an application that seeks to modify a housing and productivity contribution condition imposed under section 7.28, unless the Minister has approved the proposed modification under section 7.28(6).
Section 4.55(1) applications do not require notification, and the maximum fee is the lowest of any pathway, around $95 in the 2025-26 financial year. For a developer, the practical discipline is to be honest at the categorisation stage. The Department’s guidance tells councils to check within seven days of submission whether an application has been put in the right pathway and is likely to meet the no-impact test, and to consult the applicant about re-lodging in the correct pathway if it has not. Lodging an ambitious change as a section 4.55(1) to chase the 14-day clock, when it plainly carries some impact, tends to cost time rather than save it.
Section 4.55(1A): minimal environmental impact
Section 4.55(1A) is for modifications that do involve some change to environmental impact, but only where that impact remains minimal. The Department’s practice note reads “minimal” in its ordinary sense of very small or negligible. Two separate requirements have to be satisfied: the consent authority must be satisfied that the modification would result in only minimal environmental impact, and it must be satisfied that the development as modified would be the same or substantially the same as the development originally approved. The “minimal environmental impact” limb controls the nature and extent of the impact; the “substantially the same” limb, dealt with in detail below, controls the scope and scale of the change.
Because section 4.55(1A) involves a change to environmental impact, notification may be required, and the application is assessed on its merits rather than being subject to the 14-day deemed non-refusal clock. Typical section 4.55(1A) changes include internal reconfigurations, amended landscape plans, drainage design amendments, and minor external changes that do not materially affect privacy, height, overshadowing or streetscape. The maximum fee is the lesser of around $859 (in 2025-26 terms) or 50 per cent of the fee that was paid for the original application.
Section 4.55(2): other modifications
Section 4.55(2) is the catch-all for changes that cannot be dealt with under section 4.55(1) or section 4.55(1A). It covers modifications that would result in more than no or minimal environmental impact, but where the development as modified would still be the same or substantially the same as the development originally approved. This is the pathway for substantive design changes: altered building heights within the envelope, changed floor levels, reconfigured car parking, a different roof form, additional dwellings, or a revised unit mix, provided the development still passes the “substantially the same” gate.
Section 4.55(2) applications are assessed broadly like a scaled-down DA. They generally require notification, they are open to submissions, and they are assessed on their merits against the relevant matters. One useful change from the 2026 reforms is that the previous requirement for consent authorities to consult relevant ministers or agencies about concurrence conditions on a section 4.55(2) modification has been streamlined, which removes a source of delay on larger changes. The fee is scaled by the estimated cost of the works the modification relates to rather than being a flat amount, and where notification is required, an additional notification fee applies on top.
The table below summarises the practical differences. All fee figures are maximum fees for the 2025-26 financial year, calculated from the fee unit of $113.90 set under Schedule 4 of the Environmental Planning and Assessment Regulation 2021 (NSW). Fee units are indexed annually on 1 July, so the dollar figures will move; treat them as a guide to the order of magnitude rather than a fixed quote.
| Feature | Section 4.55(1) | Section 4.55(1A) | Section 4.55(2) |
|---|---|---|---|
| Test | Minor error, or no environmental impact | Minimal environmental impact, and substantially the same | More than minimal impact, but still substantially the same |
| Notification | Not required | May be required | Generally required |
| Determination clock | 14 days, deemed non-refusal (s4.55A) | Merit assessment, deemed refusal period applies | Merit assessment, deemed refusal period applies |
| Maximum fee (2025-26) | About $95 | Lesser of about $859 or 50% of original fee | Scaled by works cost, plus notice fee if notified |
| Typical use | Document corrections, no-impact detail changes | Internal changes, minor external changes | Substantive design changes within the same development |
The “same or substantially the same development” test
The “substantially the same” requirement is the gate that controls both section 4.55(1A) and section 4.55(2). If a proposed modification cannot be characterised as resulting in a development that is the same or substantially the same as the one originally approved, it cannot proceed as a modification at all, and the developer is back to a fresh DA. Understanding how this test is actually applied is the difference between confidently lodging a modification and wasting a fee on an application that was never going to clear the threshold.
The Department’s practice note frames the test cleanly. “Substantially” means “essentially or materially having the same essence”. The onus sits on the applicant to demonstrate that the modified development is the same or substantially the same, but it is ultimately a matter for the consent authority to be satisfied, on balance and as a matter of overall planning judgement. Crucially, the comparison is between the development as originally approved and the development as proposed to be modified. It is not a comparison against the development as previously modified, and not against what has actually been built on site. On a consent that has already been modified once or twice, this matters: the benchmark stays anchored to the original approval.
The leading authority is Moto Projects (No 2) Pty Ltd v North Sydney Council [1999] NSWLEC 280, which established that the comparison should weigh the quantitative differences (changes to height, gross floor area, setbacks and the like), the qualitative differences (changes to land use, configuration and amenity), the material and essential features of the two developments, and the consequences, such as environmental impacts, of carrying them out. For roughly three decades, councils and planners treated these as something close to a checklist, and many councils came to fixate on the quantitative differences in particular, refusing modifications that showed large numerical changes more or less on that basis alone.
That approach was firmly recalibrated by the Land and Environment Court in 2024. In Realize Architecture Pty Ltd v Canterbury-Bankstown Council [2023] NSWLEC 1437, the Court approved a modification to a large mixed-use development that added two storeys on top of an originally approved nine-storey building and an additional 2,368 square metres of gross floor area, around a 9.8 per cent increase, along with ten additional dwellings and a complete reconfiguration of the car park and communal open space. Those were among the largest quantitative differences ever approved through the modification pathway. The Council appealed, and in Canterbury-Bankstown Council v Realize Architecture Pty Ltd [2024] NSWLEC 31 the Chief Judge dismissed the appeal and endorsed a “balanced” approach to the test.
The reformulation is worth understanding because it works in a developer’s favour. The Chief Judge set out a three-step approach: first, find the primary facts, meaning identify the respects in which the originally approved development is proposed to be modified (height, bulk, scale, floor space, open space, land use and so on); second, interpret the words of the “substantially the same” test; and third, categorise the facts found, which is an evaluative exercise that involves assigning relative significance to the different facts and balancing them. The Court was explicit that the traditional formulas, comparing “quantitative” and “qualitative” differences, identifying “critical elements” or “material and essential features”, are helpful guidance but are not mandatory and do not displace the statutory words. The final categorisation can even be an “instinctive synthesis” that need not be articulated through any particular formula. The same flexible approach has been applied in cases such as Arrage v Inner West Council [2019] NSWLEC 85, and the principle that the comparison need not be undertaken in any prescribed way was confirmed by the Court of Appeal in Feldkirchen Pty Ltd v Development Implementation Pty Ltd [2022] NSWCA 227.
For a developer, the practical takeaways are concrete. Large numerical changes do not automatically fail the test; what matters is the nature, extent and effect of the differences taken as a whole. A change that increases floor area or adds height on upper levels can still be substantially the same if it preserves the nature and intensity of the use, the relationship to the public domain and surrounding development, and the essential streetscape character established by the original approval. The strongest modification cases present the comparison holistically (side-by-side elevations, three-dimensional comparisons, a “macro” rather than “micro” reading of the scheme) rather than inviting a wall-by-wall, number-by-number contest the council can pick apart. Where the call is genuinely finely balanced, it is worth getting a planning or legal opinion on the “substantially the same” question in a form that can be put to the council or panel, because a well-argued comparison is frequently what tips a marginal modification over the line.
What the consent authority must consider
The 2026 reforms also clarified the scope of the assessment itself, and the clarification is helpful to developers because it limits how far a council can reopen a settled consent. Under section 4.55(3), when determining a modification application the consent authority must consider the matters listed in section 4.15(1) of the EP&A Act, but only to the extent that those matters are relevant to the proposed modification, together with the reasons given for the original grant of consent, again only to the extent relevant. The matters in section 4.15 are the standard heads of consideration for a DA: the relevant planning instruments, the likely impacts, the suitability of the site, submissions, and the public interest.
The “only to the extent relevant” qualification is the point. A modification assessment is meant to be proportionate to the change. It is not an invitation to reassess the merits of the approved development as a whole, and it should not become a vehicle for a council to revisit issues that were settled when the original consent was granted. A developer who finds a council treating a modest modification as a chance to renegotiate the entire approval has a clear statutory basis to push back.
Two further refinements apply. Section 4.55(3A) deals with consents originally granted as “targeted assessment development”, a new streamlined assessment category introduced by the reforms; where the original consent was for targeted assessment development, the consent authority considers only the matters in section 4.15(1)(a) and (d) when assessing a modification, keeping the modification assessment consistent with the framework that applied to the original application. And section 4.55(5) confirms that a consent can be modified even where the change relates only to a condition and involves no physical change to the approved development, so a condition-only modification, for example to vary an unworkable construction-hours condition or to adjust the timing of a contribution, is assessed on its merits like any other modification.
Notification, concurrence and contributions conditions
Whether a modification has to be advertised or referred depends on the pathway and on the underlying planning controls. Section 4.55(1) applications are not notified. Section 4.55(1A) and section 4.55(2) applications may need to be notified in accordance with the relevant community participation plan, and the new section 4.55(3B) makes clear that section 4.13 of the EP&A Act applies to modification applications under section 4.55(1A) and (2) where an environmental planning instrument requires notification, consultation or concurrence. The effect is that a modification cannot be used to sidestep a notification, consultation or concurrence requirement that would have applied to the development: if the instrument requires it, it carries through to the modification.
Contributions conditions deserve particular attention because a modification that increases yield can trigger a contributions consequence. Where a modification adds dwellings or floor area, it can change the developer contributions payable under a section 7.11 or section 7.12 contributions plan, or the housing and productivity contribution under section 7.28, and a modification can also be used deliberately to vary a contributions condition. As noted above, the section 4.55A deemed non-refusal clock does not apply to an application to modify a section 7.28 housing and productivity contribution condition unless the Minister has approved it. The interaction between a yield-increasing modification and the contributions stack is one of the places where a modification can quietly erode the margin the change was supposed to protect, so it is worth re-running the numbers; our guide to developer contributions and infrastructure levies sets out how those charges are calculated and how they compound across a scheme.
Fees and timeframes
Modification fees in NSW are set as maximum fees under Schedule 4, Part 4 of the Environmental Planning and Assessment Regulation 2021 (NSW), expressed in fee units. The fee unit for 2025-26 is $113.90 and is indexed each 1 July, so the dollar figures below are current-year maxima and will rise over time. A council may charge less than the maximum, but not more.
| Modification fee item | Maximum fee (2025-26) |
|---|---|
| Section 4.55(1) modification | About $95 |
| Section 4.55(1A) modification | Lesser of about $859 or 50% of the original application fee |
| Section 4.55(2) modification, scaled by works cost | Base fee plus a per-$1,000 component; see worked example |
| Additional fee where notice is required | About $886 |
| Additional fee where a statement of a qualified designer accompanies the application | About $1,013 |
| Additional fee where referred to a design review panel | About $3,996 |
| Portal lodgement fee for a 4.55(1A) or (2) application | About $46 |
A worked example shows how a section 4.55(2) fee builds up. Take a modification to an approved apartment building where the works the modification relates to have an estimated cost of around $3 million. Under the scaled fee for works between $1 million and $10 million, the base fee is 11.54 fee units (about $1,314) plus $0.40 for each $1,000 by which the cost exceeds $1 million, which adds about $800 on a $3 million figure, for a base of roughly $2,114. If the modification has to be notified, add the notice fee of about $886, plus the portal lodgement fee of about $46. The all-up cost is in the order of $3,000 in council fees alone, before consultant and design costs. That is still a fraction of a fresh DA fee on the same development, which is part of why staying on the modification pathway is usually the cheaper route when it is genuinely available.
State significant development is handled separately. A section 4.55(1) modification of a state significant development consent attracts a fee of around $1,132, and a section 4.55(1A) modification around $6,660, reflecting the larger scale of those projects.
Timeframes vary by pathway. A section 4.55(1) application carries the 14-day deemed non-refusal clock under section 4.55A. Section 4.55(1A) and section 4.55(2) applications are assessed on their merits and are subject to a deemed refusal period, after which an applicant dissatisfied with the delay can treat the application as refused and take it to the Land and Environment Court. The 2026 reforms also expanded deemed refusal appeal rights so that, broadly, an appeal can be lodged at any time before the application is determined rather than only after a fixed waiting period has elapsed, which gives developers more flexibility about when to escalate a stalled modification. The Land and Environment Court’s Class 1 jurisdiction hears these appeals, and they are determined afresh on the merits.
Common rejection grounds, and how to avoid them
Modifications get refused, or are quietly steered into withdrawal, for a recurring set of reasons. Knowing them in advance is the cheapest form of risk management.
The first and most fundamental is failing the “substantially the same” test. A change that goes beyond alteration into radical transformation cannot be a modification, and no amount of fee or assessment will fix that. The way to manage this is to test the change against the original approval before lodging, and where it is marginal, to build the holistic comparison discussed above rather than hoping the council reads the numbers generously.
The second is pushing a change into a pathway it does not fit. A modification with real environmental consequences lodged as a no-impact section 4.55(1) application, or a substantive change lodged as a minimal-impact section 4.55(1A), will be bumped to the correct pathway after the council’s early categorisation check, costing time and sometimes a re-lodgement. Categorise honestly and lodge in the right tier the first time.
The third is a council reflexively asking for the modification to be withdrawn and a fresh DA lodged for the whole scheme, even where most of the approved development is not changing. The Land and Environment Court has been openly critical of this habit, noting that it produces delay, cost and unnecessary duplication by forcing a re-assessment of parts of a development that were already approved. A developer faced with this can point to the proportionate-assessment principle in section 4.55(3) and to the authorities confirming that large changes can be approved through the modification pathway, and can decline to be pushed onto a new DA without a sound basis.
The fourth is incomplete information. Because the comparison is against the original approval, a modification application that does not clearly identify what is changing, or that does not give the council the material it needs to be satisfied on impact, invites refusal or a request for more information that stops the clock. The fifth, related ground is using a modification to regularise unauthorised work already carried out on site; this is possible in principle but is assessed carefully, and a poorly prepared application of this kind is a common refusal.
Modifying consents granted by the Court
Section 4.55 applies to consents granted by a consent authority, typically a council, a local or regional planning panel, or the Independent Planning Commission. Where a consent was instead granted by the Land and Environment Court on a development appeal, the modification is dealt with under section 4.56 of the EP&A Act, which allows a consent authority to modify a Court-granted consent on substantially the same principles, including the “substantially the same development” test. The Court also retains the power to modify a consent it granted itself. The fee items in Schedule 4 mirror this, applying the same minimal-impact and scaled fees to section 4.56 applications as to their section 4.55 equivalents.
If a developer is dissatisfied with how a council determines a modification, the right of appeal is found in section 8.9 of the EP&A Act, which allows an appeal to the Land and Environment Court against a refusal of a modification, or against a modification granted on terms the applicant is unhappy with. The appeal must generally be brought within six months. The fee for a section 8.9 modification appeal is 50 per cent of the fee that was payable for the modification application itself. Separately, the reforms expanded the internal review pathway so that an applicant generally has up to six months to request a review of a development or modification decision, with the appeal clock paused while a review is on foot, preserving the option to litigate if the review does not resolve matters.
How modifications work in the other states and territories
NSW is not the only jurisdiction where approved consents need to change mid-project, but the mechanisms and the language differ across the country. A developer working across state lines should not assume the NSW concepts carry over. The position below is a general orientation; each state’s framework should be confirmed against its current legislation for a specific project.
Victoria
Victoria works through the Planning and Environment Act 1987 (Vic). The principal mechanism is an application to amend a permit under section 72, which is used to change what the permit allows, to change conditions, or to make significant changes to endorsed plans. A section 72 amendment broadly follows the same decision-making and appeal process as a new permit application. For minor changes, Victorian practice also recognises “secondary consent”, an administrative pathway to approve small changes to endorsed plans that does not require public notification and does not attract third-party appeal rights, although it has no express statutory basis and its limits are defined by case law. Where the Victorian Civil and Administrative Tribunal has restricted a permit so that it can only be amended by the Tribunal, the amendment must be sought from VCAT under section 87A. Our guide to planning permit applications sets out the Victorian permit process in more detail.
Queensland
Queensland deals with changes under the Planning Act 2016 (Qld) through a “change application”. The Act distinguishes a “minor change”, assessed under section 81, from an “other change”, assessed under section 82. The dividing line is whether the change would result in “substantially different development”, a concept defined in the planning framework and broadly capturing new uses, new lots, dramatic changes to built form, new or increased impacts, or increased infrastructure demand. A minor change does not result in substantially different development and need not be publicly notified; an “other change” may result in substantially different development and is assessed broadly like a new application, including possible notification. A useful feature of the Queensland regime is that, unlike the older permissible-change rules, a change that is not minor can still be made as an “other change” rather than forcing an entirely new application.
South Australia
South Australia operates under the Planning, Development and Infrastructure Act 2016 (SA) and its associated regulations, administered through the state’s online planning portal. Changes to a granted planning consent are generally dealt with by way of a variation to the development authorisation, with the assessment and notification requirements scaled to the significance of the change. As with the other states, a change substantial enough to alter the essential nature of the approved development tends to require a fresh application rather than a variation.
Western Australia
Western Australia does not use a single “modification” provision in the NSW sense. The deemed provisions for local planning schemes, set out in the Planning and Development (Local Planning Schemes) Regulations 2015 (WA), allow the holder of a development approval to apply to the local government to amend or cancel the approval, including amending the conditions, with the application assessed in a manner broadly proportionate to the change. Substantive changes that go beyond what an amendment can accommodate require a new development application.
Tasmania
Tasmania provides for the amendment of a permit under the Land Use Planning and Approvals Act 1993 (Tas), with the planning authority able to deal with amendments to a granted permit. The process and the level of assessment depend on the nature of the amendment, and a change that would fundamentally alter the approved use or development generally calls for a fresh application.
Australian Capital Territory
The ACT moved to a new framework under the Planning Act 2023 (ACT), which commenced in late 2023 and introduced an outcomes-based development assessment system. The Act provides for amending a development approval, with the pathway and assessment turning on the scale and significance of the proposed change. Developers active in the ACT should confirm the current amendment process against the Act and its regulations, as the system is still relatively new and practice continues to settle.
Northern Territory
The Northern Territory operates under the Planning Act 1999 (NT), under which the consent authority can deal with the alteration or amendment of a development permit. Minor alterations are handled more simply than substantive changes, and a change that would materially alter the approved development typically requires a new application.
A practical decision framework for developers
When a change to an approved scheme comes up, a disciplined sequence keeps the decision commercial rather than reactive.
Start by characterising the change against the original approval, not against what has been built or last modified. Ask first whether it is alteration or radical transformation. If it radically transforms the development, it is a fresh DA, and the question becomes whether the scheme still stacks up under current controls. If it is alteration, ask whether it has any environmental impact at all; a genuinely no-impact change belongs in the section 4.55(1) fast lane with its 14-day clock. If it has some impact, ask whether that impact is minimal and whether the development stays substantially the same; if so, it is a section 4.55(1A). If the impact is more than minimal but the development is still substantially the same, it is a section 4.55(2).
Then price the pathway and the delay, and run it through the feasibility. The fee is usually the small number; the real cost of a modification is the time it takes and any change it forces in yield, contributions or holding costs. Modelling the chosen pathway against the fresh-DA alternative, and stress-testing the assumptions that drive the decision, is where Feasly’s sensitivity analysis earns its place, because it shows how much margin actually rides on staying on the modification pathway and determining how hard it is worth fighting to stay there. Where the “substantially the same” call is close, the cost of a strong planning or legal opinion is almost always less than the cost of being wrong and starting again.
Key takeaways
Section 4.55 of the EP&A Act is the developer’s tool for keeping an approved development consent alive while a project evolves, and after the reforms that commenced on 21 March 2026 it is a more proportionate and, in parts, faster tool than it was. The expanded section 4.55(1) creates a genuine fast lane for changes with no environmental impact, backed by the 14-day deemed non-refusal clock in section 4.55A. Section 4.55(1A) handles minimal-impact changes, and section 4.55(2) handles substantive ones, with both gated by the “same or substantially the same development” test. That test, as recalibrated by the Land and Environment Court in the Realize Architecture decisions, is more forgiving of large numerical changes than councils have traditionally treated it, provided the essential character of the development is preserved. The strategic call that sits over all of it, modify or lodge a fresh DA, is a commercial decision worth modelling rather than guessing, because the gap between a modification fee and a full new DA, in cost, time and risk, is frequently the difference between a deal that holds and one that does not.