If a design changes after planning permission, identify the correct route before building the revised version. A small change in construction cost is not necessarily a small change in planning terms. Start with the permission, its conditions and approved drawings, then describe precisely what would change.
This guide covers the established section 96A and section 73 routes for England and when a fresh application may be needed. A lawful development certificate, prior approval and listed building consent require their own checks; they are not interchangeable with an ordinary planning permission.
Compare the three routes
| Route | What it can address | Important limit |
|---|---|---|
| Section 96A | A change the authority is satisfied is non-material | There is no universal definition or automatic size allowance |
| Section 73 | Permission to develop without compliance with specified existing conditions | It cannot change the operative description of the development or extend the commencement time limit |
| Fresh application | A proposal requiring permission beyond the available amendment route | Supporting information and consultation depend on the new application |
The government's flexible-options guidance is the starting point. The table is a route comparison, not a decision that a particular design qualifies.
First make a clear change schedule
Put the approved and proposed information side by side. For every change, record the original drawing and revision, proposed revision, dimension or specification altered, reason for the change and possible effect on neighbours or the street.
Include cumulative changes. Moving a window, raising a roof and changing a boundary treatment should not be presented as unrelated requests if together they change the scheme's effects. Identify any earlier amendment decisions and the permission being implemented.
A useful drawing comparison shows the change itself. A completely new drawing set with no revision explanation makes it harder to understand what the application is asking the authority to decide.
Section 96A: non-material amendment
Section 96A allows an authority to change a permission where it is satisfied that the change is not material. It must consider the effect of the proposed change together with previous changes under that section. Context matters: there is no national rule that moving every window by a specified distance is automatically non-material.
The decision concerns the amendment; read it with the original permission. It is not a complete replacement permission. The government guidance also explains the notification requirements for affected owners and agricultural tenants and the 28-day determination period, unless a longer period is agreed in writing.
There is no section 78 appeal right against refusal or non-determination of a section 96A application. Confirm the appropriate next application rather than assuming the ordinary planning appeal route applies.
This procedure applies to planning permission, not to changing listed building consent. For a listed property, check the separate consent requirements.
Section 73: change or remove a condition
Section 73 concerns development without compliance with conditions attached to an earlier permission. It can address a condition specifying approved plans, but the authority must be able to make the proposed change within that legal route.
Check the notice itself. Does it contain the relevant plans condition? Does the revised scheme conflict with the permission's description? The government guidance says section 73 cannot change that description and cannot extend the time within which development must begin. Do not use “minor material amendment” as a substitute for checking these limits.
A grant under section 73 is a new, independent permission alongside the original. Keep its full condition list and drawings together. Do not construct a convenient mixture of different permissions without competent advice on what can lawfully be implemented. Any associated planning obligation may also need attention; a new conditions decision does not automatically rewrite a legal agreement.
A hypothetical window and roof change
Suppose an approved extension has a high-level side window. The owner wants a wider, lower opening and a higher roof to simplify construction.
The practical question is the effect of the revised scheme: overlooking, appearance, bulk and any wording in the approved description or conditions. A designer should show both versions and explain those effects. Neither the modest budget nor the fact that the extension is already approved establishes which amendment route is available.
The owner should obtain the necessary decision before relying on the revised arrangement. If building-control design prompts the change, check the planning implications as part of the same coordination exercise. See planning permission and building regulations.
When a fresh application needs consideration
Where the change cannot lawfully be approved through the proposed amendment route, prepare a fresh planning application. Discuss the scope before producing a large document pack, but distinguish preliminary advice from an actual decision.
If work has already departed from the permission, describe the as-built situation accurately. Our retrospective planning guide explains why the sequence matters, especially if enforcement has started. An application to approve details under a condition does not itself authorise a different development.
Check the current fee category and required documents rather than carrying an old amendment fee forward. Use the application costs guide and the council's application instructions.
Proposed reforms need a separate status check
The Levelling-up and Regeneration Act 2023 includes provision for a further section 73B route. The government’s 16 July 2026 response on planning fees said it had not yet been implemented. This guide does not present that provision as an available application procedure merely because it appears in an Act. Its commencement and operational requirements must be verified before reliance. The linked current government flexible-options page explains sections 96A and 73; ask the authority to identify the legal basis of any other route it offers.
Sources and review
The linked current statutory text and government application guidance were checked on 8 September 2026 with AI assistance. The hypothetical example is an explanation of the evidence to prepare, not a decision on materiality. Complex permissions, legal agreements and already-built changes require case-specific planning/legal assessment.