Paying one does not establish that the other is included. [1][2]
What each charge is for
Borough CIL contributes to infrastructure supporting development in that authority's area. Mayoral CIL supports strategic transport infrastructure across London. Richmond's guidance explains both its local levy and its role collecting the Mayor's charge. These are separate charging arrangements rather than two names for one invoice. [3][2]
Mayoral CIL 2 took effect on 1 April 2019. The date and nature of the permission matter when identifying the applicable schedule. Do not apply the newest headline rate indiscriminately to an older permission with its own established CIL position. [1][4]
Read the indexed rate, not just the original tariff
A charging schedule may show its original base rate while an annual summary shows the indexed amount. Richmond's 2026 annual summary, for example, lists borough residential rates of £418.41 per m² in its higher band and £317.99 per m² in its lower band. Those are borough charges, not totals including Mayoral CIL. The charging-zone map determines which band applies. [5][3]
Richmond's Mayoral CIL page separately identifies a base rate of £80 per m², subject to indexation. Adding that unindexed £80 directly to an indexed borough rate would mix different price bases. Obtain the applicable indexed Mayoral figure before producing a combined estimate. [2]
These Richmond figures are a dated illustration of the two-part system. They are not rates for other London boroughs or a calculation for a particular property.
Check the calculation in two parts
Ask the project team to show the borough element and Mayoral element separately. Each should identify the relevant schedule, development type, rate year, floorspace and deductions. Then reconcile their total with the authority's liability notice. National guidance explains that CIL is calculated using the applicable rate and index, with existing-building deductions subject to specific conditions. [4]
For a mixed-use scheme or a phased permission, avoid reducing the calculation to “all floor area multiplied by one London rate”. The use categories and the permission's structure need to be checked against the actual schedules. [4]
Where relief is claimed, retain written confirmation of how it applies to the liability. The forms should go to the collecting authority, not merely remain in the designer's project folder. Richmond's guidance deals with both levies through its local CIL process. [6]
Proposed temporary London relief
The housing-support package published on 25 March 2026 included a proposal for time-limited relief from borough CIL. A further government consultation on the regulations ran from 16 July to 18 September 2026. It concerns qualifying developments and borough-level CIL, not a general cancellation of the Mayor's charge. [7][8]
A proposed relief is not an entitlement to a discount. Assess liability under the operative rules and check any eventual relief against the final eligibility, procedure and commencement provisions. [9]