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Available CIL relief

Claiming exemption or relief

Once you receive planning permission, you should submit:

  • the relevant CIL relief form
  • assumption of liability form for each party claiming relief.

The liable parties must receive acknowledgement before starting any work on the development. You can find details of relief available and a list of claim forms on the how will CIL affect my development page.

The Exemption Relief Forms Guidance sets out how to complete some of the more difficult sections.

Types of relief

Affordable (social) housing

Any social housing included within a development is eligible to claim exemption from liability to pay CIL. A relief claim must be submitted and approved before the development commences. The relevant form is a CIL Form 10.

Self-build developments

Exemption will apply to anybody who is building their own home or has commissioned a home from a:

  • contractor
  • house builder or
  • sub-contractor.

Individuals claiming the exemption must own the property.  They must also occupy it as their main home for at least three years after the works are complete.  Community group self-build projects are also exempt where they meet the necessary criteria.

Residential extensions or annexes

Residential extensions or annexes within the grounds of peoples own homes can apply for relief, if:

  • the main dwelling is the self-builder’s main house.
  • the annex is built within the curtilage of the main house and comprises one new dwelling, or
  • the extension is an enlargement of the main house and does not comprise an extra dwelling.

There is no need for the occupier of the annex to be related to the owner of the main dwelling. There is also no rule for the occupier of the annex to commit to staying there for a specified period.

Annex relief can be claimed by completing a CIL Form 8. Residential extensions exceeding 100m2 can apply for relief by completing a CIL Form 9.

Residential extensions of less than 100m2 are automatically exempt.

Exceptional Circumstances

CIL Regulations allow for relief from CIL in exceptional circumstances. This is not compulsory. The Local Planning Authority must first publish its intention for exceptional circumstances. Cornwall Council has chosen to offer Exceptional Circumstances Relief. All of the following conditions must apply, and any relief given must not constitute a notifiable state aid:

  • a Section 106 must exist on the planning permission for the development
  • the Council must agree that the cost of complying with the Section 106 agreement exceeds the CIL charge
  • paying the CIL charge would have an unacceptable impact on the development’s economic viability

Please see the Discretionary Relief policy which sets out the relief available.

Disqualifying events

Disqualifying events can occur in relation to each relief that is available. If a disqualifying event occurs within a 'clawback' period, the amount of relief granted, could become payable.

  • Social housing relief has a clawback period of 7 years. Disqualifying events include a qualifying dwelling no longer being a qualifying dwelling
  • Charitable relief has a clawback period of 7 years.  Disqualifying events include sale or letting of the property, or if the owner ceases to be a charity.
  • Self-build (whole house) exemption has a clawback period of 3 years. Disqualifying events include sale or letting of the property. Or the development ceases to meet any of the self-build criteria.
  • Self-build residential annex exemption has a clawback period of 3 years.  Disqualifying events include letting of the annex. Or selling of the annex separate to the main dwelling.
  • Self-build residential extension exemption has no clawback period or disqualifying events.

If a Form 6 is not received before the development commences, any relief granted may be withdrawn.

Development including more than 1 self-build dwelling 

Developers should consider how best to gain permission for their specific development.  This will allow relevant parties to correctly claim self-build relief.  This can be processed in a couple of ways (planning advice should be sought on the most appropriate route):

  • apply for a phased planning permission. This will allow each plot/phase to be a separate chargeable development for CIL purposes. An Assumption of Liability form can be submitted for each plot/phase along with a self-build relief claim. Commencement of part of the development would then not trigger commencement for the whole development.
  • apply for outline planning and apply for reserved matters for each individual plotThis will allow each self-build developer to assume liability and claim relief for their plot. Commencement of another part of the development would not trigger commencement for others.

If one of these routes is not followed, then a developer would need to ensure that everyone has assumed liability and claimed relief for their portion of the development before any part of it commences. Otherwise some parties may be left unable to claim relief.

Evidence needed for self-build relief

1.  You will need to provide copies of all the following items:

  1. a compliance certificate for this development issued under either: Regulation 17 (Completion Certificate) of the Building Regulations 2010 or Section 51 of the Building Act 1984 (Final Certificate).
  2. Title deeds of the property to which this exemption relates (freehold or leasehold)
  3. Council Tax bill or certificate.

2.  You will need to provide copies of two of the following items. They show your name and the address of the property as proofs of occupation of the home as sole or main residence:

  1. utility bill
  2. bank statement
  3. local electoral roll registration

3.  You will need to provide a copy of one of the following items (also see notes below):

  1. an approved claim from HM Revenue and Customs under 'VAT431NB:  VAT refunds for DIY housebuilders'
  2. proof of a specialist Self Build or Custom Build Warranty* for your development
  3. proof of an approved Self Build or Custom Build Mortgage from a bank or building society for your development.

*Relates to warranties that you can take out on a new build house. The Warranty inspectors also visit during the construction as well as whoever is controlling the site. Most common is the NHBC 10 year warranty. This would apply to new builds where the work has been controlled by the private approved inspector NHBC and not the Local Authority. 

LABC (Local Authority Building Control) also have their own warranty. It is done through LABC direct and not the local Building Control offices.  LABC Warranty tel number is 0800 183 1755, or you can email them at

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