What the forms cost, and what they are for
The Community Infrastructure Levy is a charge on new floor space that councils and the Mayor use to pay for roads, schools and transport. Our forms, from £49, are the paperwork around it: the additional information form that goes with a planning application, and where it applies the exemption claim and the notices that follow.
Inside a planning package the forms are included. Bought alone, they suit an owner who already has permission and needs the paperwork in order.
When the levy applies at all
It is not due on every extension. Development is potentially liable once net additional floor space reaches 100 square metres. Below that, new build of under 100 square metres creates no liability, unless one or more dwellings are created.
A small extension or loft may therefore fall outside the levy on size alone. Where they do not, the next step is the exemption.
The exemption for your own home
Residential extensions that enlarge the principal residence are exempt from the levy under the 2010 regulations. The catch is timing: the claim must be made on the right form and reach the council before the chargeable development begins.
That is the mistake we most want you to avoid. A builder who starts the foundations before the claim is accepted can make an exemption you were entitled to unavailable. We put the claim in with the planning application, and note it on your project plan.
London has two levies
Most London homeowners meet the Mayor's levy as well as the borough's. The Mayoral rate in the central boroughs of Westminster, Kensington and Chelsea, Camden and Islington is £80 per square metre, £96.97 after the indexation applied for 2026.
On a new house or a large block, those sums matter. For a home extension, the exemption usually takes them out of the budget, which is why the forms are worth getting right. Our CIL forms page lists the documents we complete.
Getting it done before you build
Tell us whether you have a planning permission yet, and when your builder plans to start. We tell you if a CIL claim applies and put the right forms in order.
The figures, with sources
100 m²
Additional floor space from which development may be liable for the levy.
Source: GOV.UK, Community Infrastructure Levy, checked 25 Oct 2026
Reg. 42
Small new builds under 100 square metres incur no levy, except where a dwelling is created.
Source: Community Infrastructure Levy Regulations 2010, regulation 42, checked 25 Oct 2026
Exempt
Extensions that enlarge the principal home are outside the levy.
Source: GOV.UK, Community Infrastructure Levy, checked 25 Oct 2026
Before start
The claim for exemption must reach the council before the work begins.
Source: Community Infrastructure Levy Regulations 2010, regulation 42B, checked 25 Oct 2026
20%
Surcharge on the notional charge when the commencement notice is late, with a cap of £2,500.
Source: GOV.UK, Community Infrastructure Levy, checked 25 Oct 2026
£80
Mayoral levy per square metre in Westminster, Kensington and Chelsea, Camden and Islington.
Source: Mayor of London, MCIL2 charging schedule, checked 17 Oct 2026
£96.97
The same band's rate per square metre after indexation for 2026.
Source: Mayor of London, CIL rates, checked 17 Oct 2026
Questions
Do I pay CIL on a loft conversion?
Often not: a loft adds little new floor space, and an extension to your own home can claim exemption. We check your case against the rules.
Who sends the exemption claim?
You do, as the owner; we complete the form and send it for you with your authority.
What if work has already started?
Tell us at once. We can say whether the exemption is still open to you and what to do next.
Why do the forms cost nothing in a planning package?
Because they are part of preparing an application, we include them in the package price rather than adding a line.
The fee for cil forms
What you get
- A check on whether your work is liable for the levy
- The additional information form completed
- An exemption claim made before work starts
- Plain notes on the notices that follow
- A reminder of the date your builder must wait for
