CIL & S106 Calculator

Community Infrastructure Levy estimation and Section 106 obligations screening

Project Details

Development Type

Region / Local Authority

Proposed Gross Internal Area Sqm (total new floorspace)

Existing Lawful Floorspace Sqm (to be deducted)

Residential Details (if applicable)

Total Dwellings / Units Total units in scheme

Affordable Housing Units CIL exempt

Self-Build Plots CIL exempt

CIL Rates & Indexation

Local CIL Rate * Per m² (£). CIL rates are set by each charging authority (often differing by use, zone and size) — look up YOUR LPA's adopted charging schedule. There is no national or regional rate.

Mayoral CIL Per m² (Greater London only — Mayoral CIL2 is banded by borough, ~£0–£80/m²). Enter the figure for your borough.

BCIS All-in TPI Index (current) Use the RICS BCIS All-in TPI figure for the year of the charging schedule's index date in force. Example values only — confirm the correct figures.

CIL Base Index (charging schedule) The index figure for the year the charging schedule took effect (stated in the schedule).

Section 106 Obligations Screening

Tick the obligations likely to apply. This produces an illustrative scenario using placeholder per-unit assumptions — S106 contributions are negotiated scheme-by-scheme against each LPA's adopted policy/SPD and viability. Treat the totals as an order-of-magnitude prompt, not a tariff.

Affordable Housing Obligation

Education Contribution

Healthcare Contribution

Transport/Highways Contribution

Open Space / Recreation

Ecology / Biodiversity Net Gain

Employment / Training

Monitoring Fee

Total CIL Liability £0

Illustrative S106 (placeholder rates) £0

Total Infrastructure Cost £0

CIL Calculation Breakdown

Gross Internal Area 0 sqm

Existing Lawful Floorspace 0 sqm

Net Chargeable Area (before exemptions) 0 sqm

Affordable Housing Exemption 0 sqm

Self-Build Exemption 0 sqm

Final Chargeable Area 0 sqm

Local CIL Rate (per sqm) £0

Index Adjustment Factor 1.00x

Base CIL Liability £0

Mayoral CIL (London) £0

Section 106 Obligations — Illustrative Scenario

Placeholder per-unit assumptions only. Real S106 is negotiated per scheme against the LPA's adopted policy/SPD and viability — confirm every figure with the authority.

Total S106 Cost £0

CIL Payment Schedule

Instalment	Due Date (from commencement)	Percentage	Amount (GBP)
N/A	N/A	-	-

CIL becomes due 60 days after commencement of development. Payment must be made before commencement unless a payment plan is agreed.

Exemptions & Relief

Important Caveats:

This calculator provides indicative estimates only. There is no national or regional CIL rate — you must enter the £/m² figure from your LPA's adopted charging schedule.
The S106 figures are placeholder planning assumptions, not LPA tariffs. Real S106 is negotiated scheme-by-scheme against adopted policy/SPD and viability.
The affordable / self-build CIL exemption here is approximated by floor-area proportion. The CIL Regulations (reg. 40) deduct the gross internal area of the specific qualifying buildings — confirm the exact exempt area.
Actual liabilities depend on planning conditions, the development specification, and compliance with CIL Regulations 2010 (as amended).
Affordable housing exemptions require the units to remain affordable in perpetuity.
Index adjustments are automatically calculated based on BCIS TPI. Check your charging schedule for indexation dates.
S106 monitoring fees are typically fixed amounts per head of terms; actual fees should be confirmed with the Local Authority.
This tool does not account for relief applications (e.g., charitable relief, exceptional circumstances) which must be applied separately.