Does existing floorspace count towards the threshold

Existing floorspace planning threshold questions almost always have two answers, because the same building is counted on two different bases. For deciding whether your application is major development, what matters is the floorspace the development creates. For deciding what you pay under the Community Infrastructure Levy, what matters is the net additional floorspace after an eligible deduction for what is already there.

So a scheme that demolishes an 800m² unit and builds 1,200m² is major development on the created floorspace, and is charged the levy on roughly 400m². One building, two sums, and plenty of applications where an agent has used the wrong one in a covering letter.

Gross created floorspace against net additional floorspace

The definition of major development sits in article 2 of the Town and Country Planning (Development Management Procedure) (England) Order 2015. For building projects the operative limb is the provision of a building or buildings where the floor space to be created is 1,000m² or more. Created, not net. Nothing in that limb invites you to subtract what you are knocking down.

The levy works the other way. Under the Community Infrastructure Levy Regulations 2010 the chargeable amount is calculated on net additional floorspace, with a deduction available for existing buildings, subject to a lawful use test the regulations set out precisely.

Why the difference exists is straightforward enough. The major development definition is about procedure, so it asks how much building is happening. The levy is about infrastructure demand, so it asks how much more floorspace will exist afterwards.

Change of use where nothing is built

A change of use with no building works creates no floorspace. The 1,000m² limb is therefore not engaged, however large the building. That catches people out, because a 3,000m² warehouse becoming a trade counter and gym feels like a big application and is often processed as a minor one.

The site area limbs can still bite. Where the application site is one hectare or more, or where the proposal falls within one of the specified categories such as waste or minerals, the scheme is major regardless of floorspace. Measure the red line before assuming minor status, and remember that yard, parking and landscaping all count towards site area.

For the levy, a pure change of use with no new floorspace usually produces no charge, because there is no net addition. Change of use plus a mezzanine, or plus an extension, is a different matter. The thresholds that follow from scheme size are set out in our note on obligations and the levy at different scheme sizes.

Demolition and rebuild on the same footprint

Replacing a building with one of similar size is the clearest illustration of the double count.

Illustrative example. A single-storey 950m² retail unit is demolished and replaced with a two-storey 1,100m² building of mixed retail and office use on the same plot. The created floorspace is 1,100m², so the application is major development: a 13 week determination period, press notice publicity and the full consultee list. The net additional floorspace is 150m², so the levy liability, if the existing building satisfies the lawful use test, is calculated on that much smaller figure. Figures here are illustrative only.

That asymmetry is worth planning for. Major status brings the longer determination period, wider publicity and often a committee decision, which affects your programme more than the levy affects your budget.

Proving the lawful existing use

The deduction depends on evidence, and this is where schemes lose money. The regulations require the existing building to have been in lawful use for a continuous period of at least six months within a defined period before permission first permits the development. Check the current wording of the regulations, because the test has been amended since the levy began.

The evidence that persuades a charging authority:

• business rates records naming the occupier and the period
• a lease or licence with dates, plus rent receipts
• utility bills showing consumption rather than standing charges alone
• dated photographs of the interior in occupied condition
• staff records, delivery notes or sales records for the period

Where the use is contested, a lawful development certificate under section 191 of the Town and Country Planning Act 1990 is the only formal route to confirming that an existing use is lawful. Apply for one before submitting the main application if the deduction is worth more than the certificate fee and the delay.

Absence of evidence is treated as absence of use. An authority is not obliged to accept your recollection that the unit was occupied until 2019.

Where existing floorspace cuts the levy bill but not the status

There is a further wrinkle on affordable housing. National policy provides a vacant building credit, under which the existing floorspace of a vacant building brought back into use or demolished is offset against the affordable housing contribution sought. The policy has conditions attached and has been the subject of repeated guidance, so check the current edition of the Framework and the Planning Practice Guidance rather than relying on a summary.

The credit affects the contribution, not the application's status. A scheme of 12 flats remains major development with a vacant building credit applied to every square metre of it. Where the credit is in play, set out the arithmetic in the Affordable Housing Statement rather than leaving the officer to construct it.

In London there is an additional layer, because referral to the Mayor depends on separate thresholds that are not the same as the major development definition, as set out in our note on Greater London Authority referable thresholds.

Vacant buildings and the last lawful use

Long-term vacancy creates two problems at once. The levy deduction becomes hard to prove, and the planning baseline for assessing impact becomes contested.

On the planning side, the comparison is with the last lawful use rather than with the empty building. A unit lawfully used for light industry generates a traffic and noise baseline even if nobody has occupied it for four years. Establish that baseline early, because it is the foundation of transport, noise and parking arguments later.

Where the lawful use has been abandoned, which is a question of fact involving the period of non-use, the condition of the building, the owner's intentions and any intervening use, the baseline may be lost altogether. That argument is specific to the site and is worth professional input before the application rather than after a refusal.

Presenting existing and proposed areas side by side

Set out a floorspace schedule on the drawings and repeat it in the Planning Statement. Three columns, not two: existing gross internal area, proposed gross internal area, and net change, each by use class and by floor. State the measurement convention you have used, and keep it consistent across every document.

Then add two sentences naming the test each figure serves. One saying which figure drives the major development conclusion and why. One saying which figure drives the levy calculation and on what deduction basis. Officers validate faster when they do not have to reverse engineer your arithmetic, and the smaller scale questions at the bottom end are covered in our note on the householder or minor single dwelling line.

Work out your thresholds before you commission anything, because major status changes the document list as well as the timetable. Browse all 66 PlanScope report types to see what a scheme of your size needs.

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.