Community Infrastructure Levy (CIL) for Self-Builders 2026/27
How Community Infrastructure Levy is calculated for self-build projects, the self-build exemption, strict claim deadlines, and what happens if you miss them.
What Is the Community Infrastructure Levy?
The Community Infrastructure Levy (CIL) is a charge that local planning authorities in England and Wales can choose to levy on most new development. It was introduced to give councils a standardised, more predictable way of funding infrastructure -- roads, schools, health facilities, parks -- needed to support growth, replacing some of the ad hoc Section 106 negotiations that previously covered this ground.
Not every council has adopted CIL. Those that have publish a "charging schedule" setting out rates per square metre for different types of development across different zones of their area. If your council has not adopted CIL, it will typically rely more heavily on Section 106 agreements instead.
CIL is a self-assessed, non-negotiable charge calculated by a formula -- unlike Section 106, which is negotiated case by case around the specific impacts of a development.
How CIL Is Calculated
The basic calculation multiplies the net additional gross internal floor area of your development by the relevant rate in the council's charging schedule, then applies an index adjustment (based on the RICS Build Cost Information Service index) to account for inflation since the charging schedule was set.
Net additional floor area means new floor area created, minus any existing floor area being demolished or converted that already existed lawfully on the site. This is a common area of dispute -- older outbuildings, garages, or agricultural buildings on a site can sometimes be offset against new floor area if they meet the criteria for lawful, in-use buildings.
Key factors affecting your CIL liability:
| Factor | Effect on CIL |
|---|---|
| Local charging schedule rate | Set per council, per zone, per development type |
| Net additional floor area | Existing lawful floor area can sometimes be deducted |
| Index adjustment | Applied annually to keep pace with build costs |
| Relevant exemptions | Self-build, social housing, and charitable exemptions can reduce liability to zero |
Because rates differ significantly by location and even by zone within the same council, two similarly sized homes in neighbouring authorities can face very different CIL bills.
The Self-Build Exemption
Anyone who builds or commissions a new home to live in themselves, rather than as a speculative development for sale, can generally claim full exemption from CIL under the self-build exemption. This applies to conventional self-build houses, custom-build homes commissioned from a package company, and some community-led housing projects.
The claim process has several strict stages:
- Before commencement: Submit Form 7 (Part 1) -- the Self Build Exemption Claim Form -- along with evidence of your intention to occupy the property as your principal residence. This must be approved before any development begins on site.
- Before commencement: Submit a separate Commencement Notice confirming the date development will start. Development must not begin before both the exemption is granted and the Commencement Notice has been acknowledged by the collecting authority.
- After completion: Within six months of completing the works, submit Form 7 (Part 2) with evidence that you have occupied the home as your principal residence -- typically council tax and utility bills, or other proof of residency.
Consequences of Missing a Deadline
CIL deadlines are applied with very little flexibility, reflecting the fact that CIL is designed to be a formulaic, administrative charge rather than a matter for case-by-case discretion.
If you miss the six-month deadline to submit evidence of occupation after completion, or if you commence works before receiving approval, the exemption can be withdrawn in full. This means the entire CIL liability -- calculated on the full floor area at the applicable rate -- becomes due immediately, and a surcharge may also be applied for failing to follow the correct procedure (commonly 20% of the chargeable amount, or a fixed amount, depending on the specific breach).
For a typical self-build home, losing the exemption can mean an unexpected liability running into tens of thousands of pounds, arriving with little warning once the council issues a demand notice.
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Even where the exemption is correctly granted, it is not permanent. You must occupy the property as your main residence for a minimum period after completion -- commonly three years. If you sell the property, let it out, or otherwise dispose of your interest within that period (subject to some limited exceptions, such as relationship breakdown or serious illness), the exemption is clawed back and the full CIL charge becomes payable, calculated on a sliding scale depending on how much of the required period has elapsed.
This clawback catches out some self-builders who intend to sell shortly after completion, whether due to changed circumstances or simply to release equity, without realising the exemption was conditional on continued occupation.
Appeals and Reviews
If you believe your CIL liability has been incorrectly calculated, or that a surcharge has been wrongly applied, there are limited routes to challenge it:
- Request a review by the collecting authority (the council) in the first instance, setting out why you believe the calculation or decision is wrong.
- Appeal to the Valuation Office Agency (VOA) for disputes specifically about the chargeable amount or floor area calculation.
- Appeal to the Planning Inspectorate for procedural matters, such as whether a surcharge was correctly imposed, or whether a claim was validly submitted on time.
Appeals must generally be lodged within strict time limits, often 60 days from the relevant decision or demand notice. Success is far from guaranteed, particularly where the underlying issue is genuine lateness rather than a procedural error by the council -- the system is designed to reward those who follow the process precisely rather than to offer broad discretion after the fact.
Extensions, Annexes and Small Developers
A separate but related exemption exists for residential annexes and extensions built by self-builders, subject to its own conditions -- notably that the annex must not be sold separately from the main house, and similar floor area and occupation conditions apply.
Small developers building more than one home for sale generally cannot claim the self-build exemption -- it is intended for owner-occupiers, not speculative building. If you are unsure whether your project qualifies, for example a self-build home that you might later choose to sell rather than occupy, it is worth taking planning advice before committing to a claim, since an unsuccessful or later-invalidated claim carries a real financial cost.
Sources
- gov.uk: Community Infrastructure Levy: self-build exemption claim forms
- gov.uk: Community Infrastructure Levy guidance
- Planning Inspectorate: Community Infrastructure Levy appeals
Frequently asked questions
What is the Community Infrastructure Levy?
The Community Infrastructure Levy (CIL) is a charge that local planning authorities can levy on new development to help fund infrastructure such as roads, schools and green space. It is calculated per square metre of new floor area, at rates set out in each council's local charging schedule, and is separate from Section 106 planning obligations.
Is CIL payable on all new homes?
Not automatically -- CIL only applies in areas where the local planning authority has adopted a CIL charging schedule, and only where the development creates net additional floor area above the relevant threshold (usually 100 square metres, or any new dwelling regardless of size). Many self-build homes qualify for a specific exemption even where CIL would otherwise apply.
How is CIL calculated for a self-build home?
CIL is calculated by multiplying the net additional gross internal floor area of the development (in square metres) by the rate set in the council's charging schedule for that type of development and location, then applying an index-linked adjustment. Rates vary significantly between councils and between zones within the same council area.
What is the self-build exemption from CIL?
Self-builders who build or commission their own home to live in as their principal residence can apply for full exemption from CIL, provided they follow the strict claim process. This includes submitting Form 7 (Self Build Exemption Claim) before commencing development and a further Form 7 (Part 2, Commencement Notice) confirming completion and evidence of occupation.
What happens if I miss a CIL self-build exemption deadline?
Missing a deadline -- particularly commencing development before the exemption is granted, or failing to submit the Commencement Notice before starting work -- can result in the exemption being withdrawn entirely, making the full CIL liability payable immediately, often with a surcharge. These deadlines are applied strictly with very limited discretion.
Can I appeal a CIL charge or a withdrawn exemption?
Yes, in limited circumstances. You can request a review by the collecting authority, and in some cases appeal to the Valuation Office Agency (for calculation disputes) or the Planning Inspectorate (for procedural matters like surcharges). Appeals must usually be lodged within strict time limits, typically 60 days, and success is not guaranteed if the underlying paperwork was genuinely late.
Do I have to live in the self-build home for a minimum period to keep the exemption?
Yes. You must occupy the property as your principal residence for a minimum period, usually three years, after completion. If you sell or let the property (other than in specific exempted circumstances) within that period, the exemption is clawed back and the full CIL charge becomes payable.
Does CIL apply to extensions and self-build annexes?
CIL can apply to residential extensions and annexes above the relevant floor area threshold, though a separate self-build exemption exists specifically for residential annexes and extensions, subject to its own claim process and conditions, including that the annex or extension must not be sold separately from the main dwelling.
How does CIL interact with Section 106 agreements?
CIL and Section 106 obligations are separate charges that can both apply to the same development, though the scope of Section 106 has narrowed since CIL was introduced to avoid double-charging for the same infrastructure items. Section 106 is generally reserved for site-specific mitigation, while CIL funds wider area infrastructure.
Where can I find my council's CIL charging schedule and rates?
Each local planning authority that has adopted CIL publishes its charging schedule on its website, showing rates per square metre for different development types and zones. You should check this early in your project, since rates and zone boundaries vary widely and are reviewed periodically by the council.
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Related reading
Section 106 Agreements and Affordable Housing: A Developer's Guide 2026/27
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CGT Property Calculator: Selling a Second Home or Rental Property 2026/27
Selling a second home or buy-to-let in 2026/27 means Capital Gains Tax at 18% or 24% on the gain above your £3,000 annual exemption, reported and paid within 60 days of completion. Full worked examples.