Proving an existing lawful use before a change of use
Every change of use argument starts from what the building is lawfully used for now. The burden of proof sits with the applicant, and a certificate under section 191 is the way to settle it before the main application goes in.
Before you can argue that a change of use is acceptable, you have to establish what the building is lawfully used for now. Officers will not take your word for it, and on a conversion the answer decides whether you need planning permission at all, whether a prior approval route is open, and what the fallback position is if the application is refused.
To prove existing lawful use you need documentary evidence covering the whole relevant period, and the burden sits on you rather than on the council. Nobody at the authority is going to go looking for it.
Why the existing use has to be settled first
Every change of use question is a comparison between two states. Section 55 of the Town and Country Planning Act 1990 makes a material change in the use of land or buildings development, so the assessment starts with what the use currently is.
Get it wrong and the consequences compound. A building you believe is in Class E use may turn out to have a last lawful use of storage, in which case the Class MA prior approval route to residential is closed, because Class MA requires the building to have been in Class E use for a continuous period of at least two years before the date of application, and vacant for at least three continuous months.
The same applies to fallback arguments. A planning statement that leans on the ability to resume a noisy commercial use collapses if that use was never lawful or has been abandoned. The related point about the planning unit and why it decides your change of use is worth settling at the same time, because the unit of assessment and the use of that unit are two halves of the same question.
Documents that carry weight with an officer
Rank your evidence by how hard it is to fabricate and how precisely it dates.
Business rates records held by the Valuation Office Agency are strong, because they record a description of the hereditament and the dates it was assessed. Council tax records do the equivalent job for residential use. Both are third party records created for another purpose, which is exactly what makes them persuasive.
Leases and tenancy agreements come next, with the permitted user clause and the term dates doing the work. Then filed accounts and VAT returns showing trading from the address, utility accounts in the trading name, insurance schedules describing the risk, and employer records.
Photographs help if they are dated and show something that ties them to the period, and aerial imagery is useful for yards, storage and open land uses. Trade directories and old advertisements fill gaps at the early end of a long period.
What carries least weight is a letter from a friend saying they remember it always being a workshop.
Statutory declarations and who should swear them
A statutory declaration is a sworn statement made before a solicitor or commissioner for oaths, and it is the backbone of most existing use cases.
Get it from the person with direct knowledge. The tenant who traded from the unit, the former owner who lived there, the accountant who prepared the accounts. A declaration from a current owner who bought two years ago and is reciting what the vendor told them is hearsay dressed up formally, and officers treat it accordingly.
Write it in the first person, state how the person knows what they are saying, give dates and periods precisely, and exhibit the documents referred to. Vague declarations invite a request for more information and lose you eight weeks.
The case law approach is that an applicant's own evidence can be enough if it is precise and unambiguous and there is no evidence contradicting it, which is the principle from Gabbitas v Secretary of State for the Environment (1985). Precise and unambiguous is the part people skip.
Where the time limits bite
An unauthorised use becomes immune from enforcement after the relevant period, at which point it is lawful. The period has changed. The Levelling-up and Regeneration Act 2023 amended the enforcement time limits in England so that a ten year period applies to breaches, replacing the previous split between four years and ten years, and it applies to breaches occurring on or after the date the change took effect.
That transition matters enormously for older cases, because a breach that had already become immune under the previous four year rule does not become enforceable again. Check the current wording of section 171B on legislation.gov.uk and the date the amendment took effect before you build a case on a remembered rule.
The practical consequence is simple. Your evidence has to cover a continuous period without material gaps, and it has to run up to the date of the application, not stop five years ago.
Gaps in occupation and abandonment
A vacant period does not automatically kill a use, but a long one can. Where abandonment is argued, four considerations are weighed: the physical condition of the building, the length of the period of non-use, whether there has been any intervening use, and evidence of the owner's intention.
None is decisive alone. A building left open to the weather for fifteen years with the roof gone, no rates assessment and a planning history showing an application for something else is a strong abandonment case. A unit empty for eighteen months with rates still paid, the fittings in place and marketing particulars on file is not. The fuller treatment of proving a use has been abandoned covers how each limb is evidenced.
Intensification is the mirror image problem. Where the use has grown rather than stopped, the question is whether the change is material, and the note on when doing more of the same needs consent sets out where that line tends to fall.
Applying for a certificate rather than asserting
You can assert the existing use in a planning application and hope the officer accepts it. Better practice on anything with value at stake is to apply for a certificate of lawfulness of existing use or development under section 191 of the 1990 Act.
The application is determined on evidence and law rather than on planning merits, so policy objections are irrelevant to it. A refusal can be appealed under section 195. A grant gives you a document that a lender, a purchaser and a future case officer all have to accept.
Sequence it properly. Apply for the certificate first, get it, then submit the change of use application relying on it. Running both together means the change of use application is determined while the base position is still in dispute.
Fees for certificates are set nationally and indexed, so check the current schedule rather than an old figure.
Presenting the evidence bundle
Put it together like something a solicitor would read.
- A schedule listing every document, its date, what it shows and which period it covers.
- The statutory declarations, each with its exhibits attached and numbered.
- A chronology in table form running from the earliest evidence to the application date, with gaps shown rather than hidden.
- A short statement of case setting out the use contended for, the period, and why the evidence meets the balance of probabilities test.
- Copies of the third party records, kept legible, with the relevant lines marked.
Show the gaps. An officer who finds a gap you concealed stops believing the rest of the bundle. An officer who sees you have identified an eleven month void and explained it with marketing particulars usually accepts the explanation. The supporting narrative sits well in a Planning Statement alongside the certificate application.
This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that a use is lawful, and you should check the position with your local planning authority or a qualified professional before relying on anything here.
Enter your postcode on PlanScope to draft the supporting statement for a change of use, then send it for professional review. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
What standard of proof applies to a lawful use certificate?
The balance of probabilities. The applicant carries the burden, and the case law approach is that the applicant's own evidence can be sufficient if it is precise and unambiguous and nothing contradicts it. In practice, third party records such as rates assessments and leases carry more weight than recollection because they were created for another purpose.
How long must a use continue before it becomes lawful?
Immunity from enforcement arises after the statutory period, after which the use is lawful. The Levelling-up and Regeneration Act 2023 moved England to a ten year period for breaches occurring on or after the date it took effect, while breaches already immune under the earlier rules stay immune. Check section 171B as currently in force.
Can I rely on a statutory declaration from the current owner?
Only for the period they have direct knowledge of. A declaration reciting what a vendor told them is hearsay and officers discount it. Get declarations from the people who actually occupied or traded from the property, written in the first person, stating how they know what they say and exhibiting the documents they refer to.
Does a vacant period destroy a lawful use?
Not automatically. Abandonment is judged on the physical condition of the building, the length of non-use, whether there was an intervening use, and evidence of the owner's intention. A short void with rates paid and fittings in place rarely amounts to abandonment. A long void with the building derelict and an application made for a different use often does.
Should I apply for the certificate before or with the change of use application?
Before. A certificate application under section 191 is decided on evidence and law rather than planning merits, and a grant gives you a document the case officer, a lender and a purchaser all have to accept. Running both at once means the change of use is assessed while the starting position is still contested.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.