Certificate of Lawfulness: What It Is and When You Need One

If your property has an extension, loft conversion, outbuilding, or other alteration that was carried out without express planning permission, there is a good chance the buyer's solicitor will ask about it. They will want to know whether the work was lawful. A Certificate of Lawfulness is the most authoritative way to answer that question.

This guide explains what a Certificate of Lawfulness is, the difference between the two types (CLUD and CLUE), when you are likely to need one as a seller, how the 4-year and 10-year immunity rules work, what the application process involves, and how it compares to retrospective planning permission and indemnity insurance.

What is a Certificate of Lawfulness?

A Certificate of Lawfulness is a document issued by your local planning authority under the Town and Country Planning Act 1990 (TCPA 1990). It confirms that a specific use of land, an existing development, or a proposed development is lawful for planning purposes. It is not a grant of planning permission. It is a statement of legal fact.

There are two types, each governed by a different section of the TCPA 1990:

CLUD — Certificate of Lawful Use or Development (existing)

A CLUD is applied for under Section 191 of the TCPA 1990. It confirms that an existing use of land, an existing development, or an existing failure to comply with a planning condition is lawful. A use or development is lawful if:

• It has the benefit of planning permission (including permitted development under the Town and Country Planning (General Permitted Development) (England) Order 2015), or
• The time limit for enforcement action has expired, making the development immune from enforcement under Section 171B of the TCPA 1990.

This is the type most sellers need. If work was carried out years ago without formal planning permission and is now immune from enforcement, a CLUD provides the definitive proof a buyer's solicitor needs.

CLUE — Certificate of Lawful Use or Development (proposed)

A CLUE is applied for under Section 192 of the TCPA 1990. It confirms that a proposed use or development would be lawful if carried out. This is useful where you want to establish before starting work that planning permission is not required — for instance, to confirm that a proposed extension falls within permitted development limits.

For sellers, a CLUE is less common than a CLUD but can be relevant if you want to demonstrate to potential buyers that a specific improvement could be made lawfully, adding value to the property without needing to apply for full planning permission.

When do sellers need a Certificate of Lawfulness?

You are most likely to need a Certificate of Lawfulness in the following situations:

Development carried out without planning permission

If you (or a previous owner) carried out building work without applying for planning permission, and the work does not fall within permitted development rights, you may need a CLUD to prove it is now lawful. This commonly arises with extensions, outbuildings, changes of use, and boundary alterations.

Permitted development with no formal record

Even if the work did fall within permitted development limits, the buyer's solicitor may request a certificate if you cannot provide other evidence (such as a lawful development certificate obtained at the time, architect's plans showing compliance with GPDO limits, or correspondence with the local authority). A CLUD removes any ambiguity.

Breach of a planning condition

If a condition attached to a planning permission was breached more than 10 years ago and no enforcement action was taken, the breach is immune from enforcement. A CLUD can confirm this.

Change of use

If the use of your property (or part of it) changed without planning permission — for example, a commercial property converted to residential use, or a garage converted into living accommodation — a CLUD can confirm that the use is lawful, either because permitted development applied or because the enforcement time limit has passed.

The 4-year rule and the 10-year rule

The concept of enforcement immunity is central to most CLUD applications. Under Section 171B of the TCPA 1990, there are time limits on the local authority's ability to take enforcement action against breaches of planning control:

Once the relevant period has passed without enforcement action, the development becomes lawful by virtue of the passage of time. At that point, you can apply for a CLUD to formalise the position.

Important: The time limit runs from when the breach was substantially completed, not from when it started. For building works, “substantially completed” means the development was largely finished and in use, even if minor finishing work remained. You will need to provide evidence of the completion date as part of your application.

Note also that deliberate concealment of a breach can allow the local authority to apply to the magistrates' court for a planning enforcement order under Section 171BA of the TCPA 1990, which effectively restarts the enforcement clock. This provision was introduced by the Localism Act 2011 specifically to address cases where developers deliberately hide unauthorised development.

How to apply for a Certificate of Lawfulness

The application process is straightforward but requires careful preparation. Here is a step-by-step overview:

Step 1: Determine which type of certificate you need

If the development has already been carried out, you need a CLUD (Section 191 application). If you want to confirm that proposed work would be lawful before starting, you need a CLUE (Section 192 application). Most sellers will need a CLUD.

Step 2: Gather your evidence

The burden of proof lies with you as the applicant. You must demonstrate, on the balance of probabilities, that the development is lawful. The following types of evidence are commonly used:

• Dated photographs showing the development in place at key dates (for example, photographs timestamped more than 4 years ago for building works)
• Building regulations completion certificates from the local authority or an approved inspector, which establish both the nature and timing of the work
• Architect's plans and drawings showing the dimensions and specification of the development
• Builder's invoices and contracts with dates confirming when the work was carried out
• Council tax records showing changes to the property layout or number of rooms
• Utility bills and installation records (for example, a gas or electricity connection to an outbuilding)
• Sworn statements or statutory declarations from you, neighbours, or previous owners confirming the development has been in place for the required period
• Aerial photographs from services such as Google Earth, which can show the development on specific dates

Step 3: Complete the application form

You apply using the standard application form, which is available through the Planning Portal (planningportal.co.uk) or directly from your local planning authority. The form asks you to describe the development, explain the legal basis for lawfulness, and provide your supporting evidence.

Step 4: Pay the fee

The application fee for a householder CLUD or CLUE is currently £258 (as of 2024). This is set by The Town and Country Planning (Fees for Applications, Deemed Applications, Requests and Site Visits) (England) (Amendment) Regulations. There is no fee where the sole basis for lawfulness is that the enforcement time limit has expired (Section 191(4) applications in certain circumstances), although in practice most authorities expect the standard fee.

Step 5: Wait for the decision

The local authority has 8 weeks from the date of a valid application to determine it. During this period, they may request additional evidence or carry out a site visit. Unlike a planning application, there is no public consultation — the authority simply assesses whether the evidence demonstrates lawfulness on the balance of probabilities.

If the authority fails to determine the application within 8 weeks, you can appeal to the Planning Inspectorate for non-determination under Section 195 of the TCPA 1990.

What happens if your application is refused?

If the local authority is not satisfied that the development is lawful, they will refuse the certificate. This can happen for several reasons:

• Insufficient evidence that the 4-year or 10-year time limit has passed
• Evidence that the development does not fall within permitted development limits
• Contradictory evidence (for example, photographs suggesting the development is more recent than claimed)
• Lack of clarity about what exactly was built or when

A refusal does not automatically trigger enforcement action, but it does alert the authority to the existence of potentially unauthorised development. In practice, some authorities will investigate further after a refusal, so you should be prepared for this possibility.

If your application is refused, you have two main options:

1. Appeal to the Planning Inspectorate. Under Section 195 of the TCPA 1990, you can appeal against the refusal of a Certificate of Lawfulness. The Inspector will review the evidence afresh and can grant the certificate if satisfied. Appeals are determined by written representations in most cases and typically take three to six months.
2. Submit a fresh application with stronger evidence. There is no limit on the number of times you can apply. If you can gather additional evidence — for example, a statutory declaration from a neighbour or more dated photographs — you can resubmit.

Certificate of Lawfulness vs retrospective planning permission

Sellers sometimes confuse a Certificate of Lawfulness with retrospective planning permission. They are fundamentally different and serve different purposes:

In short: if your development is genuinely lawful (because it was permitted development, or because the enforcement period has expired), you should apply for a Certificate of Lawfulness. If it is not lawful and cannot become lawful through the passage of time, you need retrospective planning permission. For more on the planning permission check before selling, see our separate guide.

How buyer's solicitors view Certificates of Lawfulness

Understanding what the buyer's solicitor is looking for helps you prepare effectively. When a buyer's solicitor reviews a property with alterations, they follow a hierarchy of evidence:

1. Express planning permission — the strongest evidence, showing the local authority actively approved the development
2. Certificate of Lawfulness (CLUD or CLUE) — formal confirmation from the local authority that the development is lawful
3. Evidence of permitted development compliance — architect's plans, measurements, and correspondence showing the work falls within GPDO limits
4. Indemnity insurance — a fallback that covers the financial risk but does not confirm lawfulness

A Certificate of Lawfulness sits just below express planning permission in this hierarchy. Most solicitors and mortgage lenders will accept a certificate without further enquiry. Indemnity insurance, by contrast, is viewed as a last resort and may not be acceptable to all lenders. Some solicitors will advise their clients that indemnity insurance carries a residual risk and may recommend negotiating a price reduction.

If you are selling a property with an extension that was not formally approved, see our guide on selling a house with an extension for advice on how buyer's solicitors approach these situations specifically.

Practical steps for sellers: what to do before you list

Taking action before you put your property on the market is far more effective than reacting to enquiries during the sale. Here is what to do:

1. Audit every alteration. Walk through your property and list every alteration or addition, including work carried out by previous owners. Check whether each item has planning permission, building regulations approval, or evidence of permitted development compliance.
2. Check your property's planning history. Search your local authority's online planning register for all applications associated with your address. This will show you what has been formally approved. See our guide on planning permission checks before selling for step-by-step instructions.
3. Identify gaps. For any alteration that does not have express planning permission or a clear permitted development justification, consider whether a Certificate of Lawfulness is needed. The 4-year and 10-year rules under Section 171B will determine which route applies.
4. Gather evidence early. Start collecting dated photographs, building regulations certificates, invoices, and any other documentation that supports lawfulness. If you need statutory declarations from neighbours, approach them well before you list.
5. Apply for a CLUD if needed. Allow at least 8 to 12 weeks before you expect to accept an offer. The application costs £258 for householder development, and most authorities take the full 8 weeks to determine it.
6. Check building regulations separately. A Certificate of Lawfulness covers planning control only. You will also need building regulations completion certificates for structural work. If these are missing, see our guide on what to do if you have no building regulations certificate.
7. Provide everything to your solicitor upfront. When you instruct your solicitor, hand over the certificate, building regulations documents, and all supporting evidence. This allows them to prepare the contract pack and anticipate any enquiries from the buyer's side.

Common scenarios where sellers need a certificate

To illustrate how Certificates of Lawfulness work in practice, here are the scenarios that arise most frequently in property sales:

Rear extension built more than 4 years ago without planning permission

A homeowner built a single-storey rear extension 6 years ago without applying for planning permission. The extension exceeds permitted development limits (it is 5 metres deep on a semi-detached house, exceeding the 3-metre PD limit). Because more than 4 years have passed since the work was substantially completed, it is immune from enforcement under Section 171B(1). A CLUD application with dated photographs, builder's invoices, and a statutory declaration from a neighbour confirms lawfulness.

Garage converted to living space with no change of use application

A previous owner converted the garage into a bedroom 12 years ago without any planning application. Converting a garage to habitable space within the curtilage of a dwelling does not always require planning permission if it remains ancillary to the main dwelling, but where it involves a material change of use (for example, creating a self-contained unit), planning permission is required. In this case, the 10-year rule has passed, so a CLUD can confirm the current use is lawful.

Outbuilding that may exceed permitted development limits

A garden office was built 2 years ago. The seller believed it was permitted development, but the buyer's solicitor has queried whether it meets the height and boundary distance requirements of Class E of the GPDO 2015. If the outbuilding does comply with PD limits, a CLUE (or CLUD) application can confirm this with measurements and plans. If it does not comply and fewer than 4 years have passed, the seller may need to apply for retrospective planning permission or arrange indemnity insurance.

Breach of a planning condition more than 10 years ago

A condition on the original planning permission for a property required that a specific window be fitted with obscured glass. The window was replaced with clear glass 15 years ago. The breach of condition is immune from enforcement under the 10-year rule (Section 171B(3)), and a CLUD can confirm this.

Costs, timescales, and what to expect

Here is a summary of the practical details for a householder Certificate of Lawfulness application:

If you instruct a planning consultant or solicitor to prepare and submit the application on your behalf, expect to pay an additional £300 to £800 in professional fees, depending on the complexity of the case.

Sources

• Town and Country Planning Act 1990, Section 191 (certificate of lawfulness of existing use or development) — legislation.gov.uk
• Town and Country Planning Act 1990, Section 192 (certificate of lawfulness of proposed use or development) — legislation.gov.uk
• Town and Country Planning Act 1990, Section 171B (time limits on enforcement) — legislation.gov.uk
• Town and Country Planning Act 1990, Section 171BA (planning enforcement orders) — legislation.gov.uk
• Town and Country Planning Act 1990, Section 195 (appeals against refusal of certificates) — legislation.gov.uk
• Town and Country Planning (General Permitted Development) (England) Order 2015 (SI 2015/596) — legislation.gov.uk
• The Town and Country Planning (Fees for Applications, Deemed Applications, Requests and Site Visits) (England) (Amendment) Regulations — legislation.gov.uk
• Planning Portal — Lawful development certificates: guidance — planningportal.co.uk
• GOV.UK — Guidance on lawful development certificates
• Localism Act 2011, Section 124 (planning enforcement orders) — legislation.gov.uk
• Royal Institution of Chartered Surveyors (RICS) — Certificate of Lawfulness practice information — rics.org
• Law Society — Property Information Form (TA6) guidance — lawsociety.org.uk

Frequently asked questions