Using a permitted development fall-back in an application

A fall-back argument says that if the application is refused, something else will be built instead, and that the something else would be worse or no better. Where the alternative is permitted development, the argument can be powerful, because the decision maker is being asked to compare the proposal against a scheme the applicant does not need permission for. Permitted development fall-back as a material consideration is well established. What defeats most attempts to use it is evidence, not principle.

The test is whether there is a real prospect of the fall-back being carried out. Not a theoretical possibility. A real prospect, on the evidence, judged at the date of the decision.

What a fall-back argument actually is

The logic runs in three steps. There is a lawful alternative the applicant could implement without permission. There is a real prospect they would implement it if this application fails. The harm from that alternative is equal to or greater than the harm from the proposal, so the proposal's harm is not a reason to refuse.

The Court of Appeal in Mansell v Tonbridge and Malling Borough Council in 2017 confirmed that the question is one of planning judgement for the decision maker, and that the prospect has to be real rather than merely theoretical. The weight given to a fall-back is then a matter for the decision maker, which means even a well evidenced fall-back does not compel an outcome.

Two limits are worth stating early. A fall-back does not cure a conflict with the development plan. It goes into the balance as a material consideration alongside everything else. And it only helps where the comparison favours the proposal, which is not always obvious once the alternative is drawn properly.

Showing a real prospect of implementation

The evidence that persuades is documentary, dated and specific.

Start with lawfulness. A certificate of lawfulness of proposed use or development under section 192 of the Town and Country Planning Act 1990, granted before the application is determined, removes the argument that the alternative might not be permitted development at all. Where the alternative requires prior approval, obtaining that approval does the same job, and how the prior approval procedure actually works sets out the timescales involved.

Then show intent and capability:

• Drawings of the fall-back scheme prepared to the same standard as the application drawings, not a sketch.
• A costed build for the fall-back, showing it is affordable and deliverable.
• A statement from the applicant or landowner explaining what they would do if refused, and why.
• Evidence of ownership and control of everything the fall-back needs.
• Where relevant, evidence that the fall-back would be commercially rational, which on a residential scheme usually means a value comparison.

The weakest fall-back cases are the ones where the applicant has never drawn the alternative. An inspector reading a paragraph asserting that a large extension could be built under Class A, with no drawing and no costing, is being asked to take the point on trust.

Where the argument tends to fail

Inspectors have been sceptical of fall-backs in three recurring situations, and those patterns are indicative of how the issue is approached rather than binding rules.

The first is where the fall-back would be plainly unattractive to the applicant. A scheme that produces a worse building, costs more and sells for less is not one a rational developer would build, and asserting otherwise invites the response that the prospect is not real.

The second is where the fall-back has not been tested for lawfulness. Permitted development rights are conditional, and the conditions are detailed. An assumed Class A extension that breaches a limit, or an upward extension that fails one of the Class AA conditions, is not a fall-back at all. The limits and conditions for those routes are set out in Class A rear extension limits and the larger home extension scheme and Class AA upward extensions and prior approval.

The third is timing. Permitted development rights can be removed by an Article 4 direction or by condition on an earlier permission, and rights that exist when the application is submitted may not exist when it is determined. A fall-back that depends on a right the council is consulting on removing is a fragile one.

Comparing harm honestly

Once the fall-back is established, the comparison has to be drawn in the terms the decision maker uses, which means harm by category rather than a general impression.

Set out a table comparing the proposal and the fall-back on each issue in play: scale and massing, effect on neighbouring amenity, effect on the character of the area, trees, parking, and any designated asset. Be specific about what is worse and what is better. A comparison that claims the fall-back is worse in every respect is less credible than one that concedes a point.

The comparison should be drawn against what could lawfully be built, not against the worst thing imaginable. Drawing a maximal fall-back that technically complies but that nobody would ever build weakens the case, because the realism of the fall-back is exactly what is being tested.

Where the proposal is better in planning terms than the fall-back, say so in one sentence and support it with the drawings. That sentence is the whole argument, and burying it in three pages of analysis does it no favours.

Securing the fall-back before you apply

The strongest position is one where the fall-back is not an argument at all but a fact. A granted certificate of lawfulness, or a completed prior approval, converts a contested proposition into a document with a reference number.

Programme it. Certificate applications take time, and running one in parallel with the main application means the certificate may arrive after the committee report is written. Where the timing is tight, submit the certificate application first and the main application once it is determined, accepting the delay in exchange for the certainty.

There is a cost consideration too. A certificate application carries its own fee and its own drawing package, so the fall-back route is not free, and on a modest scheme the cost may exceed the value of the argument.

Presenting it in the planning statement

Put the fall-back in its own section of the Planning Statement, not scattered through the policy analysis. The section should state the lawful alternative, the evidence that it is lawful, the evidence that it would be implemented, the comparison of effects, and the weight the applicant invites the decision maker to give it.

Attach the fall-back drawings as an appendix and reference them by number. Officers write reports under time pressure, and a fall-back that can be understood from one drawing and one table is one that makes it into the report accurately.

Invite a specific weight rather than asking for the argument to be accepted in the abstract. Saying that the fall-back should carry substantial weight because it is certified lawful and costed is a proposition the officer can adopt or reject. Saying that a fall-back exists is not.

And accept that a fall-back is a supporting argument. If the scheme only works because something worse could be built, the scheme has a problem the fall-back will not fix.

This is general guidance, not legal advice, and a Lawful Development Certificate is the only formal way to confirm that works are lawful. 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.