Proving the lawful existing use of a building

To prove lawful existing use of a building you apply for a certificate under section 191 of the Town and Country Planning Act 1990, and you win or lose on documents. The council does not have to disprove your case. You have to establish, on the balance of probabilities, that the use has been carried on continuously for long enough to become immune from enforcement, or that it is otherwise lawful. Landlords and investors need this more often than they realise, because almost every conversion, permitted development route and levy calculation is priced off the existing lawful use rather than the actual one.

Why the existing use governs what you can change to

The baseline determines everything downstream. A change of use application is judged against what the building lawfully is now, not against what the last occupier happened to do.

Three consequences follow for anyone buying to convert. Permitted development routes carry qualifying-use conditions, so the office to residential route depends on the building having been in the relevant commercial class for a stated period before the application. The existing floorspace deduction against the Community Infrastructure Levy depends on the building having been in lawful use for a continuous period of at least six months within the three years before the permission first permits development. And the materiality of any proposed change is assessed against the lawful baseline, so a building wrongly assumed to be in Class E may not enjoy the flexibility described in our note on changes of use within Class E.

Get the baseline wrong and the error compounds. A purchase priced on a Class E assumption, with a levy saving assumed and a permitted development route assumed, can lose all three at once.

The certificate of lawfulness route under section 191

Section 191 lets any person apply to the local planning authority for a certificate that an existing use of land, operations already carried out, or a failure to comply with a condition, is lawful. Section 192 does the same for something proposed.

A certificate is not a planning permission and it is not discretionary. The authority is deciding a question of fact and law. Planning merits, neighbour objections and policy have no place in it, which is why a use that would never be permitted today can be certified if it has run long enough.

Once granted, the certificate is conclusive for the purposes it states, binds the authority, and goes on the planning register. Refusals are appealed to the Planning Inspectorate, and the appeal is again about evidence and law rather than about whether the use is acceptable.

Fees differ between the two routes. An application for an existing use attracts the same fee as an application for planning permission for that use would. An application for a proposed use attracts half that amount. Check the current schedule, since fees are indexed.

Statutory declarations and who should make them

Statutory declarations do the heavy lifting in most successful applications, and their quality varies enormously.

A useful declaration is made by someone with direct personal knowledge, states how they know what they know, covers a defined period with dates, and describes the use in concrete terms. "I collected rent from the workshop on the first Friday of every month between March 2011 and July 2019 and the occupier manufactured window frames throughout" is evidence. "The building has always been industrial" is not.

Collect them from a spread of sources: the owner, successive occupiers or tenants, employees, the accountant, the letting agent, neighbours, and trades who visited regularly such as a waste contractor or a boiler engineer. Independent declarations carry more weight than the applicant's own, although the guidance is clear that an applicant's uncorroborated evidence can be accepted where the authority has nothing to contradict it.

Have declarations made properly before a solicitor or commissioner for oaths. A false declaration is an offence, which is exactly why they carry weight.

Rates records, accounts and utility evidence

Documentary evidence anchors the declarations to dates.

• Business rates records and the rating list entry, which show the described use and the period of assessment. Useful, though the rating hereditament is not the planning unit.
• Council tax records where a residential use is being established.
• Accounts, VAT returns and tax records showing trading from the address across the period.
• Tenancy agreements, licences, rent books and rent demands, which give continuity between occupiers.
• Utility bills and meter readings, which show consumption consistent with the claimed use, and which are especially valuable in proving that a building was in use rather than standing empty.
• Insurance schedules describing the trade carried on.
• Employment records, payroll addresses and delivery notes.

Gaps are the enemy. A run of evidence with a two-year hole invites the authority to say the use ceased, so fill the gap with something even if it is only a single dated invoice.

Photographs, directories and aerial imagery

Images date things that documents cannot.

Dated photographs of signage, plant, stock and vehicles are worth assembling from the owner, from former staff and from local history collections. Commercially available aerial and street-level imagery from successive years shows vehicles, fencing, extensions and hardstanding appearing and disappearing, and can be printed with the capture date shown.

Trade directories, old advertisements, local newspaper archives and archived versions of the occupier's website all place a business at an address on a date. Where a building was extended or altered, historic mapping and the building control record may show when.

Present all of it in a single schedule cross-referenced to a chronology, rather than as an appendix of loose items. An officer who can follow the timeline in one table approves faster than one who has to build it themselves.

Time limits and the effect of the 2023 Act

Immunity from enforcement depends on time limits in section 171B, and those limits changed.

The Levelling-up and Regeneration Act 2023 made the ten year period general in England, and the change applies to breaches occurring on or after the date it took effect. A breach that was already immune before then does not become vulnerable again, and one that began before the change keeps the old period. Identify the date the breach began before you decide which limit applies, because that date decides the case.

Continuity through the period is a requirement, not a formality. A use that stopped and restarted may have broken the run, and a long cessation can amount to abandonment, judged on the physical condition of the building, the length and circumstances of the non-use, the owner's intentions and any intervening use. Deliberate concealment is a separate trap: the courts have held that concealment can prevent reliance on the time limits, and authorities can apply for an order extending their enforcement window in such cases.

Standard of proof on the applicant

The burden sits with the applicant and the standard is the balance of probabilities. National guidance puts it plainly: the applicant's own evidence does not have to be corroborated by independent evidence to be accepted, and where the authority has nothing to contradict it or make the account less than probable, there is no good reason to refuse.

That is a lower bar than people expect, and it is often lost by presentation rather than by substance. Applications fail because the description of the use is vague, because the period claimed does not match the evidence supplied, because the plan does not match the description, or because the applicant claimed more than the evidence supported and the whole submission lost credibility.

Claim precisely what you can prove. A certificate for a narrower use is worth far more than a refusal for a wider one, and the planning unit analysis matters here too, as set out in our note on ancillary use and the separate planning unit.

Using the certificate to support a later application

Once granted, the certificate does three jobs.

It fixes the baseline for any subsequent change of use application, and it should be cited by reference number in the Planning Statement rather than paraphrased. It evidences the qualifying use where a permitted development route depends on the building having been in a particular class. And it supports the existing floorspace deduction in the levy calculation, which on a building of any size is frequently worth more than the fee and the professional costs combined.

It also settles the question for a lender and a purchaser, which is why the certificate is often best obtained before exchange rather than after. Where the wider change of use strategy is the immediate question, our note on proving an existing lawful use before a change of use covers how the certificate fits into that sequence.

To see which supporting documents a change of use proposal is likely to need, enter your postcode on PlanScope and run the constraint check.

This is general guidance, not legal advice. Certificates of lawfulness turn on the facts and the evidence, so take advice from a qualified professional before relying on any of it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.