Walkthrough: section 73 to amend an approved housing scheme

A section 73 application varies a condition on an existing permission. It does not amend the permission, and it cannot change the description of the development, so the first question on any amendment is whether what you want to do fits inside that limit. The walkthrough below is illustrative, written to show the sequence on a small housing permission rather than to describe a real site.

The illustrative permission is for six detached houses on a former paddock, granted eighteen months ago, with conditions including a list of approved drawings, a landscape scheme, a drainage strategy and an access specification. Nothing has been built. The owner, a self-builder taking the scheme forward plot by plot, wants to enlarge plot 4 by 1.8 metres to the rear, move the shared access three metres north to improve visibility, and change the roof covering on two plots from slate to a clay pantile.

The permission and the condition to be varied

Three of the four changes are caught by one condition: the approved plans condition, which lists the twelve drawings the development must accord with. Enlarging plot 4, moving the access and changing a roof covering all mean building something other than what those drawings show.

The access change is also caught by a separate condition requiring the access to be formed in accordance with a named drawing before first occupation, so the section 73 application has to vary both conditions or the permission becomes internally inconsistent.

This is the part most often got wrong. An applicant varies the approved plans condition, the council grants it, and a second condition elsewhere on the notice still refers to a superseded drawing. The new permission then requires two incompatible things.

Whether the change is within the scope of section 73

Section 73 allows permission to develop land without complying with conditions previously imposed. The courts have held that it cannot be used to vary a condition in a way that conflicts with the operative description of the development, so a permission for six houses cannot become a permission for seven by varying the plans condition.

Applying that here:

• Enlarging plot 4 by 1.8 metres: within scope, because the development is still six detached houses.
• Moving the access: within scope, for the same reason.
• Changing the roof covering: within scope, and arguably so minor that the alternative route below fits better.
• Adding a seventh plot: outside scope. That needs a fresh application.

The alternative route for trivial changes is a non-material amendment under section 96A, which amends the existing permission rather than creating a new one, is quicker and costs less, and is decided without re-consultation. A roof material change on two plots might well be accepted as non-material by itself. Bundled with a footprint change and an access relocation it will not be, so in the illustrative case everything goes into one section 73 application. The distinction between the two routes is set out in section 73: varying a condition without starting again.

How an approved plans condition binds

An approved plans condition is stronger than most applicants expect. Building otherwise than in accordance with the listed drawings is a breach of condition, enforceable by a breach of condition notice, and it can also take the development outside the permission altogether where the departure is substantial.

That matters at the margins. A window moved 300 millimetres is a departure from the drawing, and in practice nobody enforces it. A rear wall moved 1.8 metres changes the relationship with the boundary, the overshadowing analysis and often the drainage layout, and a building control inspection record showing the as-built position is exactly the document an enforcement officer will ask for later.

So vary it properly. The schedule of changes should list every drawing being superseded, with the old number and revision against the new, and should identify each substantive change in a sentence. Officers approve amendments quickly when they can see what changed and slowly when they have to compare twelve drawings themselves.

The biodiversity gain condition on an amended scheme

This is the part of section 73 practice that has changed most since 2024, and it needs checking case by case rather than assuming.

Under the Environment Act 2021 regime a biodiversity gain condition is deemed to be attached to most planning permissions, with the Biodiversity Net Gain Assessment and the gain plan sitting behind it. Regulations made under that Act deal with section 73 permissions, including where the original permission was granted before the regime started, and where the condition did apply to the original permission the gain plan may need revisiting for the amended scheme.

In the illustrative case the original permission predates the start of the regime, which is why the applicant checked the position with the authority before submitting rather than after. The answer changes the programme, because a metric assessment and a gain plan on a six unit scheme is weeks of work by a competent person, and the statutory metric is not something the applicant can complete themselves.

The wider point applies to any technical condition. Where the amendment touches drainage, ecology, highways or landscape, the supporting document behind that condition needs updating and submitting with the application, not offering later.

Consultation on the varied scheme

Section 73 applications are publicised like any other. Neighbours are re-notified, site notices go up where required, and consultees are re-consulted where the change affects their interest.

That is a real risk on an amendment and applicants underestimate it. The neighbours who did not object to the original scheme now receive a letter about a house moving 1.8 metres closer to their boundary, and some of them will object to the whole development rather than to the change. Officers assess only the change, but a committee trigger based on objection numbers does not distinguish.

Two mitigations are worth the effort. Write to the affected neighbours yourself before submitting, with a drawing showing the change. And in the covering statement, state plainly what is not changing, so that the officer's report has a paragraph to point at when objections range wider than the amendment.

Highway authority re-consultation on the access change is where the illustrative application spent most of its time, because moving the access three metres altered the visibility splay calculation and required a revised access plan.

The new permission and the old conditions

A section 73 grant creates a new, freestanding planning permission that sits alongside the original. The original is not cancelled and remains capable of implementation, which occasionally matters if the amended scheme turns out to be undeliverable.

Because it is a new permission, the whole set of conditions has to be carried across. Check the draft notice for four things: that every condition from the original appears unless deliberately omitted, that conditions already discharged are recorded as such or omitted, that no condition refers to a superseded drawing, and that pre-occupation and pre-start triggers still make sense given that the scheme is part built or unbuilt. The mechanics of the new permission and what carries over are covered in section 73 variations and the new permission they create.

There is a separate trap with planning obligations. A section 106 agreement tied to the original permission does not automatically bind the new one, so a deed of variation or a supplemental deed is usually needed. On the illustrative scheme there was no agreement, which is one reason the amendment was straightforward.

The submitted pack

For the illustrative application the pack was:

1. The application form for removal or variation of a condition, with the fee at the current published rate.
2. A copy of the original decision notice and the approved drawings being superseded.
3. A schedule of changes, drawing by drawing, with a one line description of each change.
4. The revised drawings, clearly numbered as new revisions.
5. A short planning statement explaining why each change falls within the scope of section 73 and addressing the policy effect of the change only.
6. A revised access and visibility plan, and a note from the drainage engineer confirming the strategy still works.
7. A schedule of conditions proposed for the new permission, marking those already discharged.

Item seven takes an hour and saves a fortnight, because it gives the officer a starting point for the new notice.

Timing against the original time limit

The single hard constraint. Section 73 cannot be used to extend the time limit for implementing a permission, and a permission granted under it carries the time limit of the original. So if the original permission must be implemented within three years of its grant, the section 73 permission must be implemented by that same date, whenever it was granted.

On the illustrative scheme eighteen months of a three year permission had gone, and the section 73 took four months. That left fourteen months to make a lawful start, which was comfortable. Leave the amendment until month thirty and it is not.

Where time is short, implementing the original permission first and then applying to vary conditions on the implemented permission is a route worth taking advice on. The section 73 checklist before you submit covers the rest of the groundwork.

The 2023 planning legislation introduced a further route for varying permissions where the development is not substantially different from what was approved, with the dates on which it takes effect to be verified, so check whether it is available in your case.

This walkthrough is illustrative and is general guidance, not legal advice. Confirm the scope of section 73, the biodiversity gain position and the time limit with your local planning authority or a qualified planning professional before relying on it.

PlanScope can draft the planning statement and supporting documents for an amendment, and you can browse all 66 report types to see which need updating. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.