Section 106 / CIL Estimator

CIL is a charge that local authorities can choose to set on new development to fund infrastructure (roads, schools, parks). It is charged per square metre of net additional floor space at rates set by each council in its own CIL charging schedule under the CIL Regulations 2010 — there is no national or regional rate. Rates vary significantly, from £0 in the many areas with no CIL (including Manchester and most Welsh councils) to over £300/m² in parts of London. The statutory charge is also adjusted for inflation using the BCIS All-in Tender Price Index. CIL helped fund generic infrastructure that was previously pooled through Section 106.

Section 106 (of the Town and Country Planning Act 1990) agreements are legal obligations negotiated between developers and local authorities as a condition of planning permission. They typically cover affordable housing provision, education contributions, healthcare infrastructure, open space, and other site-specific requirements that cannot be addressed through CIL.

In England, affordable housing is normally sought on ‘major’ developments — 10 or more dwellings, or sites of 0.5 hectares or more (NPPF, December 2024). The percentage and tenure split are set by the local authority’s adopted Local Plan policy and typically range from 20-40% of units, subject to a viability assessment. In designated rural areas, councils may apply a lower threshold of 5 units. Some councils accept a financial contribution in lieu of on-site provision for smaller schemes.

There is no fixed rate. Education contributions are calculated using the DfE methodology (‘Securing Developer Contributions for Education’, August 2023): the expected pupil yield from the new homes multiplied by the DfE building-cost multiplier (the per-pupil-place cost). Pupil yield depends heavily on the dwelling mix — larger family homes generate more school-age children, and many councils exempt 1-bed flats. As an indicative guide, contributions commonly fall in the region of £3,000 to £12,000+ per dwelling for a typical mixed scheme, but they vary widely by county and dwelling size. Always confirm the figure against your local education authority’s adopted formula.

Yes, both can apply. Before September 2019, Regulation 123 of the CIL Regulations 2010 restricted using Section 106 for infrastructure that CIL was intended to fund (councils published a ‘Regulation 123 list’) and limited pooling to five obligations per project. The CIL (Amendment) (No.2) (England) Regulations 2019 — in force 1 September 2019 — repealed Regulation 123 and removed both the pooling restriction and the ‘double-dipping’ ban, so authorities can now use CIL and S106 toward the same infrastructure. Transparency is instead provided through annual Infrastructure Funding Statements (Regulation 121A, required from December 2020). In practice CIL still tends to fund generic infrastructure while S106 covers site-specific needs, primarily affordable housing.