Document - Section 4.55 Modification - Changing an approval without starting again
What is a Section 4.55 Modification and How Do I Change My DA?
You have spent months getting your Development Application (DA) approved. But now that you are looking at the final plans, you realize you want to move a window, have some minor changes to the layout or change the roof material.
Do you have to start the whole DA process again from scratch? Thankfully, no. In NSW, there is a streamlined process for amending an approved design. It is called a Section 4.55 Modification.
What is a Section 4.55 Modification?
A Section 4.55 Modification is the formal mechanism that allows an approved Development Application to be amended. Instead of lodging a brand-new DA, you “reopen” the existing approval and apply only for the specific changes you want to make.
Because Council assesses just the proposed amendments—rather than reassessing the entire development—the process is typically faster, simpler, and more cost-effective than starting from scratch. For many residential projects, it is the most practical way to refine a design as it moves closer to construction.
The "Substantially the Same" Test
The most important rule governing a Section 4.55 Modification is the requirement that the development remain “substantially the same” as what was originally approved. This does not mean the design must be identical, but it must retain its fundamental character, scale, and intent.
For example, increasing a four-bedroom modern home to five bedrooms is usually acceptable because the overall building type remains unchanged. On the other hand, transforming a two-storey dwelling into a three-storey apartment building would clearly fail the test, as the nature of the development has been fundamentally altered.
If Council determines that a proposal is no longer substantially the same, the modification will be refused and you will be required to lodge a new DA. This not only increases costs but also resets the assessment timeline.
When is it required?
A Section 4.55 Modification must be approved before the change is built. It is critical not to rely on advice such as “we’ll build it now and fix the paperwork later.” Any construction that does not match the approved DA plans is considered unlawful.
If a neighbour raises a complaint or Council conducts a site inspection, this can result in a Stop Work Order or, in serious cases, a requirement to demolish unauthorised works. The safest and most cost-effective approach is always to obtain approval for the modification first.
Common Pitfalls and Professional Advice
One of the most common mistakes homeowners make is underestimating the cumulative impact of multiple small changes. Individually, each alteration may seem minor, but together they can push a project beyond what Council considers “substantially the same.”
A practical strategy is to bundle all proposed changes into a single modification application. Lodging multiple Section 4.55 applications not only increases Council fees but also creates unnecessary administrative complexity. At OAK Architecture and Design, we work closely with clients to identify all desired changes upfront and consolidate them into a single Section 4.55(1A) application wherever possible.
How to obtain a Section 4.55 Modification
Obtaining a Section 4.55 Modification is a coordinated process involving both architectural and planning expertise. We begin by updating the approved DA drawings, clearly marking every proposed change so Council officers can quickly identify what is new and what remains unchanged. These “clouded” drawings form the visual basis of the assessment.
A Town Planner is then engaged to prepare the modification report. Their role is critical: they provide the planning justification and demonstrate, in professional terms, that the amended design remains substantially the same as the original approval. A well-prepared planning argument significantly reduces the risk of Council requesting a new DA..
Change your mind, not your timeline.
Design refinement is a normal and expected part of the building process. When managed correctly, a Section 4.55 Modification allows you to improve your project without jeopardising your approval or delaying construction. If you need experienced guidance to adjust your design while keeping your DA secure, OAK Architecture and Design can help you move forward with confidence.
