Material change of use: what it means in planning
Section 55 makes a material change in the use of land or buildings development, so it needs permission. Materiality is judged on the facts, against the planning unit.
A material change of use is development, and development needs planning permission. That is the whole of the material change of use definition in section 55(1) of the Town and Country Planning Act 1990, which defines development as the carrying out of building, engineering, mining or other operations in, on, over or under land, or the making of any material change in the use of any buildings or other land.
The word doing the work is material. Every use changes a little over time, and the planning system is not interested in most of it. A change is material where it has consequences the planning system cares about, judged as a question of fact and degree by the decision maker on the evidence in front of them.
What section 55 says, and what it takes back out
Section 55(2) lists things that are not development even though they might look like it. Four matter to most readers.
Works of maintenance, improvement or alteration that affect only the interior of a building, or that do not materially affect its external appearance, are not development. This is why a full internal refit needs no permission while a new shopfront usually does.
The use of any building or other land within the curtilage of a dwellinghouse for any purpose incidental to the enjoyment of the dwellinghouse is not development. A home office in a garden building, used by the household, sits here. A business with staff and visitors does not.
The use of land for agriculture or forestry, and of buildings occupied with that land for those purposes, is not development. The buildings themselves may still need consent, and the agricultural exemption is narrower than most rural clients expect.
A change of use from one use to another within the same class of the Use Classes Order is not development. That exemption is why movements inside Class E, which covers shops, offices, restaurants, clinics, gyms and light industry compatible with a residential area, pass without an application.
Section 55(3) then deems two things to be material changes. The first is the use as two or more separate dwellinghouses of a building previously used as a single dwellinghouse, which is why subdividing a house always needs permission. The second concerns the deposit of refuse or waste, where extending the area covered or raising the height above the adjoining land is a material change even though the land was already used for tipping.
Materiality is judged against the planning unit
You cannot assess materiality without first fixing the land you are assessing. That area is the planning unit, and identifying it is a separate exercise set out in our article on how councils decide what they assess.
The same activity produces different answers on different units. Forty square metres of trade counter sales inside a 400 square metre warehouse is an ancillary element of a storage use. The same activity in a separate 40 square metre unit with its own access is a retail use replacing a storage use.
Once the unit is fixed, the question is whether the character of the use of that unit has changed in a way that matters in planning. Officers look at what the land is used for, who comes and goes, when, in what numbers, with what vehicles, and what effects follow for neighbours and the highway.
Intensification and the cases that are hard
Doing more of the same is the difficult category. Section 55 catches changes of use, and a mere increase in the amount of an existing activity is not automatically a change at all.
The test is whether the intensification has changed the character of the use. A bed and breakfast with two letting rooms that grows to eight, with commercial signage, daily servicing and a licensed bar, has changed character on any reading. The same house letting one extra room has not. Between those two lies a wide grey zone, and the honest answer is that many cases in it cannot be predicted with confidence without a certificate application. Our note on intensification works through the indicators councils weigh.
Household cases follow the same logic through the incidental exemption. An annexe occupied as part of the household is incidental. The same building occupied independently, with its own kitchen, entrance and council tax banding, is a separate dwelling and a material change of use. The occupation test is set out in annexe or separate dwelling.
An illustrative worked case
Illustrative example, for method only. A ground-floor unit in a parade is in retail use within Class E. The occupier begins preparing hot food for collection, then for delivery, and by the end of a year the unit trades from 5pm to 11pm with a delivery rider waiting area on the forecourt and extraction ducting to the rear.
Retail and restaurant uses are both within Class E, so a movement between them would not be development. Hot food takeaway is not within Class E. It is a sui generis use, which means it sits outside the classes and any change to it is a material change of use requiring permission.
The evidence a council would collect looks unremarkable: the hours displayed in the window, the delivery platform listings, complaints about riders and odour, and a photograph of the new duct. The planning judgement then turns on hours, odour, noise and highway effects, which is why an application of this kind is usually supported by an Odour Assessment and a ventilation and extraction case.
Where people get it wrong
Use classes are treated as the whole answer. They are not. The Use Classes Order exempts movements within a class, and everything else still has to be tested against section 55.
The second error is assuming a change of occupier is a change of use. It is not, of itself. A new tenant running the same activity in the same way changes nothing in planning terms.
The third is reliance on old immunity rules. Enforcement time limits in England changed in 2024 to a single ten-year period for most breaches, replacing the four-year period that previously applied to operational development and to change of use to a single dwellinghouse. Anyone relying on the passage of time should check the current position in the legislation rather than repeating the old rule.
And the fourth is the belief that a change made quietly will simply become lawful. Immunity has to be proved, on the balance of probabilities, with continuous evidence across the whole period.
Settling the question on your own site
Where a change is proposed, the choice is between applying for permission and applying for a lawful development certificate under section 192 of the 1990 Act, which asks the council to confirm that the proposed use would be lawful. Where a change has already happened, section 191 does the same for an existing use.
Either way the evidence pack matters more than the argument:
- A plan of the site with the asserted planning unit outlined.
- A description of the existing use and the proposed use, in activity terms rather than by class label alone.
- Floor areas by activity, opening hours, staff and visitor numbers, and vehicle movements.
- Dated evidence covering the period relied on, such as invoices, accounts, tenancy agreements, photographs and utility bills.
- Where the case turns on effects, the supporting assessments the council would expect on a full application.
A Planning Statement that sets out the unit, the character of the existing use and the character of the proposed use, in those terms, answers the question the case officer has to ask. PlanScope drafts one from your site details and flags the facts it cannot verify rather than filling them in.
This is general guidance, not legal advice. 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.
Frequently asked questions
What makes a change of use material?
A change is material where the character of the use of the planning unit has altered in a way the planning system cares about. Councils look at the activity, hours, visitor and vehicle numbers, servicing and the effects on neighbours and the highway. It is a question of fact and degree, decided on the evidence rather than by formula.
Is moving within Class E a material change of use?
No. Section 55(2)(f) takes changes within the same use class outside the definition of development, so a shop becoming an office, a clinic or a gym within Class E needs no permission. Moving to a use outside the class, such as a hot food takeaway or a drinking establishment, does need permission.
Does splitting a house into flats need permission?
Yes, always. Section 55(3)(a) deems the use of a building as two or more separate dwellinghouses, where it was previously a single dwellinghouse, to be a material change of use of the building and of each part of it. No permitted development right covers it, and building regulations approval is a separate requirement.
Can a use become lawful through the passage of time?
Yes, but it must be proved. Enforcement time limits in England changed in 2024 to a single ten-year period for most breaches. The applicant carries the burden of showing continuous use across the whole period on the balance of probabilities, which in practice means dated documentary evidence rather than recollection.
What is the difference between section 191 and section 192?
Section 191 certifies that an existing use or operation is lawful, usually because it has permission or is immune from enforcement. Section 192 certifies that a proposed use or operation would be lawful if carried out. Both are decided on evidence and law, not on planning merit, and both carry a right of appeal.
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.