Advice on calculating the levy
In calculating Gross Internal Area (GIA) chargeable area the definitions in the RICS Code of Measuring Practice, 6th Edition, 2007 are relied upon.
In general terms any internal area all floors including rooms, circulation space such as lifts and floorspace devoted to corridors, toilets, storage, conservatories, garages and other ancillary buildings are included. For a full list of inclusions and exclusions please click on the following link.
To ensure that the chargeable area is calculated correctly and in accordance with the Council's Local Validation List 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.) and the internal space should be annotated to indicate the existing/proposed use (s). Demolition of existing buildings or walls should be clearly shown. Your floor plans should also indicate the thickness of external wall and any other evidence you consider relevant to your submission.
- View the Local Validation List for advice on calculating the levy.
When verifying your GIA calculations the Council will accept a 1-5% margin of error.
In accordance with Regulation 40 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. 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 matches a use that could have lawfully been carried out without requiring a new planning permission. Because there must be a lawful use, parts of the building where the use has been abandoned cannot be taken into account here. The Council will require evidence of lawful use for the time period required. Evidence may include records from business rates, environmental health, licensing, bank statements, council tax records and utility bills.
CIL Calculator
This calculator should be used for guidance only and is not a formal determination of CIL liability.
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Please note, calculator does not include index of inflation charges.
Indexation
In calculating individual charges for the Levy, Regulation 40 (as amended by the 2014 Regulations) requires collecting authorities to apply index of inflation to keep the levy responsive to market conditions. This index presents forecast figures, which are updated and finalised annually. Regulation 40 (6) states the index figure for a given year is the figure for the 1st November for the preceding year in the National All-In Tender Price Index of construction costs published by the Building Cost Information Service (BCIS) of the Royal Institution of Chartered Surveyors.
From 1 January 2020 local authorities in areas which charge the levy should use the figure for 1 November for the preceding calendar year. See the ‘Community Infrastructure Levy (Amendment) (England) Regulations 2019’.
The Index is an annual index and the figure to be used from 1 November each year will be published in October.
RICS CIL Index (base 1985 mean = 100)
| Year | Index | Published |
| 2024 | 381 | 23 October 2023 |
The index is based on the BCIS All-in Tender Price Index (BCIS TPI). The index is published on the same base as the BCIS All-in Tender Price Index used in the previous regulations. The 2024 figure is based on building prices in 2023 and will apply from 1 January 2024.
The index will be published on the fourth Monday in October each year. The Index, once published, will not normally be subject to revision. Should RICS feel it necessary to amend a published Index this will only be done with the agreement of MHCLG and details will be provided on the Webpage.