Confirming permitted development with a lawful development certificate

A lawful development certificate is the only way to get a council to confirm in a binding document that your works are permitted development. Under section 192 of the Town and Country Planning Act 1990 you can apply for a certificate that proposed works would be lawful, and under section 191 for a certificate that existing works or an existing use already are. Neither is a planning application. You are not asking whether the council likes the scheme. You are asking it to state the legal position.

That distinction changes how the application is written. Design merit is irrelevant. Measurements, dates and evidence are everything.

What sections 191 and 192 certificates do

Section 192 deals with the future. You describe the works or use you intend, and if the council agrees they would be lawful, it issues a certificate. Once issued, the lawfulness of what you described is conclusively presumed, unless there is a material change in circumstances before you carry it out.

Section 191 deals with the past. You describe works already carried out or a use already established, and the council certifies that it is lawful, whether because it always was permitted development or because it is now immune from enforcement through the passage of time.

The burden of proof sits on you in both cases, and for a section 191 application the standard is the balance of probabilities. Unchallenged, credible evidence from the applicant can be enough on its own. Vague recollection is not.

Enforcement time limits changed under the Levelling-up and Regeneration Act 2023, which moved the four year period for operational development and for change of use to a single dwellinghouse to ten years in England, with commencement in 2024 applying to breaches occurring from that point. The transitional position matters if your works are of an age that straddles it, so check the current position before relying on a four year argument.

When a certificate is worth the fee

Not every extension needs one. Most do not. The cases where it earns its cost are specific.

• The measurements are close to a limit, such as a rear extension at or near the depth cap, or an eaves height within a few centimetres of the boundary restriction
• The plot has an unusual shape or a sloping ground level, so the reference point for height is arguable
• The curtilage has been altered, with land added from a neighbouring plot or a former paddock, which is dealt with in measuring curtilage and the enlarged garden
• A previous extension exists and the cumulative limits are in play
• The house may have been a former agricultural building or converted barn, where permitted development rights can be restricted by condition
• You are selling or remortgaging and the buyer's solicitor has asked for proof
• A neighbour has complained and the council has written asking what you are doing

The last one is the strongest case. Once an enforcement officer is involved, a certificate application moves the argument onto documents and away from a conversation on the doorstep.

Evidence needed for a proposed operation

For a section 192 application the evidence is drawings and a legal argument. There is no site history to prove.

Provide a site location plan, a block plan showing the whole curtilage with the original dwellinghouse marked as it stood on 1 July 1948 or as first built if later, existing and proposed floor plans, existing and proposed elevations, and a section through the sloping part of the site where levels matter. Then set out, class by class and condition by condition, why the proposal complies. Quote the Order: Schedule 2, Part 1, Class A, then the specific limitation letter you are addressing.

Councils respond well to a compliance table. One column for each limitation in the class, one for the proposal's figure, one for the drawing reference that proves it. It converts a judgement into a check.

Be exact about the original dwellinghouse. The limits in Part 1 are measured against the building as originally built or as it stood in 1948, not as it stands today, and that single point defeats more permitted development claims than any other.

Evidence needed for existing works

For a section 191 application you are proving what happened and when. Assemble the documents rather than relying on a narrative.

1. Dated photographs, ideally with something in frame that fixes the date, plus the original digital files with their metadata where you have them.
2. Invoices and receipts from builders, suppliers and skip hire, showing addresses and dates.
3. Bank or card statements corresponding to those invoices.
4. Council tax records, utility bills or insurance documents showing the property as altered.
5. Aerial imagery from dated sources, and historical mapping.
6. Statutory declarations from the applicant and from independent witnesses, such as a neighbour or the builder, made before a solicitor.
7. Any building control records, completion certificates or warranty documents.

A statutory declaration on its own is weaker than the same declaration supported by three invoices. Where a document is missing, explain why rather than leaving a gap for the officer to fill with doubt.

Drawings and measurements the council expects

Scale drawings, properly dimensioned, prepared to a recognisable standard. Sketches are refused.

The measurements officers check first are depth from the original rear wall, overall height, eaves height where within two metres of a boundary, the proportion of the curtilage covered by buildings, the width of a side extension against the original dwelling, and the position relative to the principal elevation. Show each of them as a dimension on the drawing rather than in the covering letter alone.

Where the ground slopes, show the datum. Height under the Order is measured from the highest part of the adjacent ground, and a section drawing with levels marked is the only way to demonstrate the figure.

Fees, timescales and appeals

The fee for a certificate is tied to what a planning application for the same development would cost. A proposed use or development certificate under section 192 attracts a proportion of that figure, while an existing use or development certificate under section 191 attracts the equivalent full amount. Application fees are set by national regulations and indexed annually from 1 April, so check the current schedule rather than a figure quoted in an older article.

The determination period is eight weeks. There is no requirement for neighbour consultation, because the application is about law rather than merits, although some councils notify anyway.

If the council refuses, or issues a certificate in narrower terms than you asked for, there is a right of appeal to the Secretary of State under section 195. Appeals are decided on the evidence, so the quality of the original submission largely determines the outcome.

What the certificate does and does not protect

A certificate confirms the planning position and nothing else. It does not deal with Building Regulations approval, the Party Wall etc. Act 1996, restrictive covenants in your title, protected species obligations under the Wildlife and Countryside Act 1981, listed building consent, or the rights of a freeholder or management company.

It also does not survive a change in the facts. A section 192 certificate covers the development as described, so if you build it differently, the certificate does not cover what you built. And the conclusive presumption is subject to a material change in circumstances before the work is carried out, which includes an Article 4 direction made in the meantime.

A permitted development fall-back can also carry weight in a planning application for something larger, and a certificate is the cleanest way to establish that the fall-back is real rather than theoretical, as covered in the permitted development fall-back as a material consideration.

Using the certificate at sale or remortgage

Conveyancers ask for evidence that works were lawful, and the alternatives are a certificate, an indemnity policy, or a seller's statutory declaration that the buyer's solicitor may not accept. A certificate closes the point permanently and transfers with the property, because it attaches to the land rather than to the owner.

Allow the eight weeks. A certificate applied for at the point of exchange is a certificate that arrives after completion.

Illustrative example: a homeowner builds a 3.8 metre rear extension on a semi-detached house with a 250 millimetre fall across the site, then decides to sell two years later. The buyer's solicitor queries whether the eaves height complied within two metres of the boundary. A section 191 application with a section drawing showing the datum, the builder's invoices and a statutory declaration is granted in seven weeks. Details are illustrative.

Where a full application turns out to be needed instead, PlanScope drafts the Planning Statement and other supporting documents from your site details, flagging missing facts rather than inventing them. Enter your postcode on PlanScope to see which documents the works are likely to need.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.