Calculating CIL

CIL charges are based on the net amount of floorspace in square metres coming forward with a development. The existing or proposed floorspace of a development is measured using Gross Internal Area (GIA) and the Council will use the RICS Code of Measuring Practice, 6th Edition, 2015  to determine what constitutes GIA for the purposes of calculating the Levy.

In general terms any internal area of all floors including rooms, circulation space such as lifts and floorspace devoted to corridors, toilets, storage, conservatories, garages and other ancillary buildings are included but roof spaces which are not useable rooms, for example, accessed by loft ladder/loft hatch or void areas are not.

To ensure that the chargeable area is calculated correctly, existing and proposed floor plans should be drawn at a metric scale (typically 1:50 or 1:100) and must include a scale bar. Each floor should be clearly titled (typically as ground floor, first floor etc). Demolition of existing buildings or walls should be clearly shown. The GIA of all relevant areas should be included within the CIL Additional Information Form (Form 1)

• CIL additional information form 

When verifying your GIA calculations the Council will accept a 1-5% margin of error.

In accordance with Schedule 1 of the CIL Regulations (as amended) where part of an existing building has been in lawful use for a continuous period of 6 months within the past three years, parts of that building that are to be demolished or retained can be taken into account in calculating net floorspace.

Where an existing building does not meet the six-month lawful use requirement, its demolition (or partial demolition) is not taken into account.

However, parts of that building that are to be retained as part of the chargeable development can still be taken into account if the intended use following completion is a use that is able to be carried on lawfully and permanently without further planning permission in that part on the day before planning permission first permits the chargeable development.