01Planning
Community Infrastructure Levy forms for London homes
Most house extensions pay no Community Infrastructure Levy, but only if the right form reaches the council at the right time. Miss a step and a charge or a surcharge can follow. We work out whether you are liable and file each form in order. From £49, fixed before we start.
From £49
- MCIAT chartered architectural technologists
- £2m professional indemnity insurance
- LABC Partnered
- ICO registered
02The fee
One fixed fee, published
What you get
- A written view on whether your scheme is liable for the levy, by floor area and type
- The CIL additional information form, completed from your drawings
- An exemption claim for a residential extension or annexe, sent before work starts
- The commencement notice at the right moment, so no surcharge arises
- A dated record of each form to keep with your deeds
The forms are free inside our planning packages. On their own the fee is {{price}}, with no VAT to add. The levy itself, where payable, goes to the council and the Mayor.
03How it runs
The CIL paperwork in order
100 m²
Net additional floor space at or above which development is potentially liable for the levy. Source: gov.uk
04Planning
Most extensions are exempt, if you ask
The levy is aimed at new floor space of 100 square metres or more. Development whose new build is under 100 square metres gross is not chargeable, unless it includes a new dwelling. Residential extensions that enlarge the main home are exempt from the levy too, whatever the size, but the exemption must be claimed.
The claim has to be on the government form and received by the council before the chargeable development begins, and a claim lapses if work starts before the council decides it. The rule that required a commencement notice first was dropped in England in 2019; the claim itself is the first form.
05Planning
When the levy does bite
A new dwelling pays the levy whatever its size. In London the Mayor's charge applies as well as the borough's: Westminster, Kensington and Chelsea, Camden and Islington are in the Mayor's band one, at £80 a square metre in the charging schedule, which rises each year with indexation to £96.97 for 2026.
The borough adds its own rate where it has set one. We say on the quote whether a charge is likely, so you can put the figure into the appraisal before you buy the site or sign the build contract.
06Planning
The mistake that costs money
The commonest error is not about the form but its timing. A commencement notice must go in before work starts on site, and a late one carries a surcharge of 20 per cent of the notional charge, capped at £2,500. A self-builder who starts on a Monday and sends the notice on Friday can lose an exemption altogether.
We keep the dates on your project diary and send each form as its trigger arrives. They sit with your planning drawings and your building regulations drawings, so the builder's start date and the council's records agree.
07The record
Figures that shape the job
100 m²
Net additional floor space at or above which development is potentially liable for the levy.
Source: Planning Practice Guidance, Community Infrastructure Levy, paragraph 001, checked 25 Oct 2026
<100 m²
New build under 100 square metres gross internal area creates no liability, unless it includes a dwelling.
Source: Community Infrastructure Levy Regulations 2010, regulation 42, checked 25 Oct 2026
Exempt
Residential extensions that enlarge the principal residence are exempt from the levy.
Source: Planning Practice Guidance, Community Infrastructure Levy, paragraph 049, checked 25 Oct 2026
Before start
An exemption claim must reach the council before the chargeable development begins.
Source: Community Infrastructure Levy Regulations 2010, regulation 42B, checked 25 Oct 2026
20%
Surcharge on the notional charge for a late commencement notice, capped at £2,500.
Source: Planning Practice Guidance, Community Infrastructure Levy, paragraph 004, checked 25 Oct 2026
£80
Mayoral CIL band one rate 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 band one rate per square metre after indexation for 2026.
Source: Mayor of London, indexed MCIL rates 2026, checked 17 Oct 2026
08Questions
What clients ask before they instruct us
Do I pay CIL on a house extension?
Normally not: residential extensions that enlarge the main home are exempt. The exemption must be claimed before work starts, and we file the claim for you.
What if the council has already sent a liability notice?
Send it to us. We check the figure and, if an exemption applies, claim it before the commencement date. After work starts the exemption can be lost.
What do the forms cost?
From £49 with no VAT to add, or nothing extra inside our planning packages. We confirm the exact fee in the quote.
Does a new house in a garden pay the levy?
Yes: a new dwelling is chargeable whatever its size. We estimate the charge up front so you can put it in the appraisal; see planning drawings for the application itself.
Do you file the commencement notice for my builder?
We prepare and send it once your builder confirms the start date, and log it. It must go in before work starts on site.
09Related
Related services and guides
Send us the address of your house.
We look up the conservation area, listing and Article 4 position, then reply with a fixed fee. A message before 3pm is answered the same working day.