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Calculating CIL

The Community Infrastructure Levy (CIL) is calculated using a formula, indexation, our charging schedule and any exemptions or relief granted.

The amount of CIL payable will depend on the size, type and use of the development site. This information must be provided as part of the planning application. It is in your interest to submit the CIL question form, even if you believe you are not liable, so that we can determine whether the development is CIL chargeable and ensure that the charge is calculated accurately. Failure to provide this information will mean that we will not validate the application. All plans will be checked when submitted.

Gross Internal Area (GIA)

CIL is calculated using the Gross Internal Area (GIA) of new floor space of  development. The floor space is then multiplied by the charge for that use type. Where there are a number of use types proposed within a development, the floor space will be split accordingly by type and then multiplied by the relevant charges.

GIA measures the internal area of each floor of the building, including circulation and service space such as corridors and includes areas such as storage rooms, toilets, lifts etc. These types of internal communal areas are also included in the calculation as part of the chargeable development, Generally, any structure with 3 or more walls and a roof is considered to be ‘internal’ floor space and therefore chargeable. GIA is set out in the Code of Measuring Practice produced by the Royal Institute of Chartered Surveyors (RICS).

Existing uses

The gross internal floor space of any existing buildings on the site that are going to be demolished, retained or reused may be deducted from the calculation of the CIL liability. The charge will be based on the floorspace of the new buildings less the floorspace of the demolished or retained buildings, e.g. the net increase in floorspace. However, these deductions only apply where the demolition or retention relates to a building which has been in its continuous lawful use for at least six months in the last three years, prior to when planning permission is granted. The building must also have been in situ at the time.

Where only a small part of the planning unit to be demolished or retained has been in use for over six months in the last three years prior to the development being permitted, all the floorspace in the building would be deductible from the floorspace of the new buildings.

CIL formula

The calculation of the CIL chargeable amount is defined by the CIL Regulations:

R x A x IP

R = the levy rate as set in the Maidstone Charging Schedule.  
A = the net area of floor space chargeable in square metres after deducting any existing floor space and any demolitions, where appropriate.
IP = the index figure for the year in which planning permission was granted
IC= the index figure for the year in which the charging schedule took effect (2018)

The value of A must be calculated by applying the following formula:

Regulation 40 (calculation of chargeable amount) paragraph (6) of the 2010 regulations has been substituted with -

(6) The value of A in paragraph (5) must be calculated by applying the following formula:

GR – KR – (GR x E)



G = the gross internal area of the chargeable development;
GR = the gross internal area of the part of the development chargeable at rate R;
E = an amount equal to the aggregate of the gross internal areas of all buildings which—
a) on the day planning permission first permits the chargeable development, are situated on the relevant land and in lawful use; and
(b) are to be demolished before completion of the chargeable development; and

KR = an amount equal to the aggregate of the gross internal area of all buildings (excluding any new build) on completion of the chargeable development which—
a) on the day planning permission first permits the chargeable development, are situated on the relevant land and in lawful use;
b) will be part of the chargeable development upon completion; and
c) will be chargeable at rate R.

Index linked

Calculations must include an index rate, as set out in the regulations, in line with the All-in Tender Price Index of construction costs (provided by the BCIS). CIL rates are index linked to track building cost inflation, and reflect changes in the cost of delivering infrastructure. The indexation is calculated to track the change between the rate at the point CIL was introduced, and the rate at the point a planning permission is granted.

Indexation is for the calendar year from 1 January to 31 December. Our charging schedule ‘takes effect’ from 1 October 2018 so for the period of October through to the end of December 2018 the CIL levy will be as per the agreed charging schedule. Indexation will be added from 1 January 2019 and each subsequent year in the future, the index may increase or decrease. MBC will publish each year the RICS CIL Index figure it will be using for indexation, this will be based on the figure published by RICS on the fourth Monday in October of the preceding year.

CIL charges

Rates are applied depending on the planning use, and the location of the development. CIL rates are based on financial viability. Types of development that are less viable will have a no charge.

Our approved charges from 1 October 2018.

Development type/location CIL charge per square metre

Residential (within the urban boundary)

Residential (outside the urban boundary) £99
Site H1 (11) Springfield, Royal Engineers Road,
Retirement and extra care housing *1 £45
Retail - wholly or mainly convenience *2 £150
Retail - wholly or mainly comparison (outside the town
centre boundary) *2
All other forms of CIL liable floorspace £0

These will change annually in line with indexation. For more information on indexation please see regulation 6 legislation.