How far an application can be amended before redetermination

An application can be amended during determination as long as the development remains in substance the one that was applied for and nobody who should have been consulted is deprived of a chance to object to what is now proposed. That is the Wheatcroft principle, and it is the test a council applies when your architect sends revised drawings in week six. Change the roof form and you are fine. Add two units and change the access, and you are looking at a fresh application.

Officers apply the test intuitively rather than by reference to the authority. Knowing what actually governs it makes the conversation much shorter.

The principle that governs amendments

The rule comes from a 1982 challenge concerning a reduction in the number of dwellings on an application, where the court held that an amendment may be accepted provided the development is not so changed that to grant permission would deprive those who should have been consulted of the opportunity to make representations they would have wished to make.

Two points follow that people often miss. The test is about prejudice to consultees rather than about the size of the change, so a small alteration in a sensitive position can fail where a large one in an unimportant position passes. And the test is the same whether the change makes the scheme better or worse, because a neighbour may want to comment on an improvement as much as on a deterioration.

There is no statutory procedure for amending an application. The statutory publicity requirements in the Development Management Procedure Order 2015 attach to the application as submitted, and what happens afterwards is governed by the common law duty of fairness and by the authority's own practice.

That is why answers vary between councils. Some re-consult on every revision, some on none, and the difference is administrative habit rather than law.

The test of substantial difference and prejudice

Work through four questions when you are deciding whether a change is safe.

1. Does the description of development still describe what is proposed? If the description says "erection of 6 dwellings" and there are now seven, the description is wrong and the application is for something else.
2. Does the red line boundary still contain the whole development? Expanding the site is almost always a fresh application.
3. Would a reasonable objector who read the original publicity have anything new to say about the revision? If the answer is plainly yes, re-consultation is needed at minimum.
4. Has a statutory consultee's basis for its response changed? A highways response given on a 6-unit scheme does not carry over to eight.

The practical rule is that an amendment reducing impact is easier than one increasing it, and an amendment that leaves the description intact is easier than one that does not.

Amendments before and after the decision

Before the decision, the Wheatcroft test applies and the authority has a discretion. After the decision, the position changes completely, because the permission is a legal document and amendment means altering it.

Post-decision routes are three. A non-material amendment under section 96A of the Town and Country Planning Act 1990 handles minor changes only, with the limits set out in our note on section 96A non-material amendments. A section 73 application varies or removes a condition, including a condition listing the approved drawings, which is how most so-called minor material amendments are actually delivered, and our guides to section 73 variations and the new permission they create and to varying a planning condition under section 73 explain the mechanics. Anything beyond those is a fresh application.

Reserved matters approvals sit outside both routes, because a reserved matters approval is not a planning permission and cannot be varied under section 73. Our note on reserved matters scope and timing covers how that plays out.

Re-consultation and when it is required

Where an amendment is material enough to affect what a consultee would say, fairness requires that they get the chance to say it. Failing to re-consult on substantially revised plans has been the basis of successful challenges, and authorities have become noticeably more cautious as a result.

Re-consultation is usually 14 days rather than the original 21, and it is normally targeted at the parties affected by the change rather than at everybody. Where the change alters what the public can see, re-advertisement may be needed as well.

Two practical consequences for an agent. First, re-consultation eats the determination period, so a revision submitted in week six of an eight-week case will need an extension of time agreed. Second, the revision restarts the objection window, and objectors who missed the first round get a second chance. That is a real risk on a contested scheme, and it is sometimes a reason to leave a marginal improvement out.

Publish the revision properly on the register. An amendment that officers accept but never publish is the weakest point in any later challenge.

Amendments at appeal

The same test applies on appeal, and the Planning Inspectorate applies it explicitly. Amended plans submitted with an appeal are accepted where the inspector is satisfied that no party is prejudiced, and rejected where the appeal would become a decision on a different scheme.

The difference is that an inspector is determining the appeal against the application the council refused. Substantially changing the scheme at appeal risks the inspector declining to consider the revision, and it can also attract an application for costs against you for the wasted work.

Where a refusal reason can be answered by a modest change, the safer routes are usually a fresh application taking advantage of any free resubmission entitlement, or agreeing the change with the authority so the amendment is uncontroversial.

An illustrative example

An application for nine dwellings refused nowhere near the boundary questions, where the officer's concern is the two-storey element closest to a listed cottage. The agent submits a revision at week seven dropping that block to single storey and pulling it 4m further from the boundary, with no change to unit numbers, access or the red line. The authority re-consults the conservation officer and the two nearest neighbours for 14 days, agrees a four-week extension of time, and approves. The same change adding a tenth unit would have needed a new application. This example is illustrative rather than drawn from a specific case.

Practical limits agents should observe

Some habits keep you out of trouble.

Never change the description of development by amendment. If the description is wrong, either the application is wrong or the change is too big.

Never expand the red line. Ransom strips, visibility splays over third-party land and construction access all have to be inside the original boundary or in a new application.

Keep a clean drawing register with revision letters and dates, and submit a covering note with every revision explaining what changed, why, and whether you consider re-consultation necessary. Officers appreciate being told, and it protects you if the decision is challenged later.

Agree an extension of time in writing at the same moment you submit the revision. It costs nothing and it prevents an awkward non-determination position.

Choosing between amendment and resubmission

The calculation is usually about time and risk rather than fee.

An amendment keeps the existing case, the existing consultee responses where they still hold, and the existing officer. It costs nothing beyond the drawing work. It risks a re-consultation that reopens objections and a determination period that has to be extended.

A resubmission starts clean, may attract no fee where a free resubmission entitlement applies within twelve months on the same site, and produces a decision that is unambiguous. It costs a full determination period and exposes the scheme to any policy change since the first submission.

On a straightforward scheme with a supportive officer, amend. On a contested scheme where the change is significant or the description is affected, resubmit and set out the changes in the Planning Statement so the second case reads as a considered response rather than a second attempt.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.