Guide Community Infrastructure Levy (CIL)

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3. Calculating CIL?

The Community Infrastructure Levy (CIL) is calculated per square metre of Gross Internal Area of floor space.

The calculation involves multiplying the CIL charging rate by the net chargeable floor area (based on Gross Internal Area), and factoring in an index figure to allow for changes in building costs over time.

The full calculation is set out under Schedule 1 of the CIL regulations 2010 (as amended).

Guidance on calculating the levy is also available on the Government’s website:

There is also guidance here regarding how the charging schedule affects Outline applications:

How is Gross Internal Area calculated? 

Gross Internal Area (GIA) measured to the internal face of the perimeter walls of each floor of the building, including circulation and service space such as corridors, storage, toilets, lifts etc and the existing floor space of a building. Generally, any structure with 3 or more walls and a roof is considered to be ‘internal’ floor space and therefore chargeable. Buildings ‘into which people do not normally go’ are exempt from CIL. These include buildings into which people go intermittently for the purpose of inspecting or maintaining fixed plant machinery.

The change of use of a floor space where a self-contained residential unit will be formed is also chargeable if the existing continuous use cannot be demonstrated.

Existing floor area that has been in continuous lawful use for a period of 6 months within the 3 year period preceding development being permitted can be used as deductible floor area in the calculation of the CIL liability. The onus is on the applicant to demonstrate continuous lawful use. Information that could be submitted to demonstrate this can include the combination of the following:

  • Copies of leases;
  • Electricity/gas bills for the six month period;
  • Business rate/council tax bills and payments (Note: The Local Planning Authority does not have access to this information as it is data protected);
  • Where an informal arrangement exists, redacted bank statements should be submitted to show to show rent has been paid;
  • Confirmation from a letting agent/solicitor advising of the period of occupancy;
  • An affidavit.

The council will require further evidence of continuous use if it is not evident from the information supplied and will not consider the existing floor area as deductible floor area unless the applicant demonstrates this.

Relevant development granted planning permission from 1 September 2016 until 1 February 2021 will be charged in accordance with the rates set out in the Council’s first Adopted Charging Schedule.

Relevant development granted planning permission from 1 February 2021 will be charged in accordance with the rates set out in the Council’s revised Adopted Charging Schedule.