Community Infrastructure Levy, explained.

Anyone may assume liability for the levy, on an assumption of liability form: ideally with the planning application and in any case before work starts, because it cannot be assumed afterwards. The council then issues a liability notice setting out the amount. If nobody has assumed liability when work starts, the levy is split between the owners of the land, surcharges can be added and the whole sum is due at once. That matters most where the person building is not the person who owns the land, because the default puts the bill on the owner.

The threshold is the gross internal area of new build; an extension below it pays nothing without any claim. At 100 square metres or more, the residential extension exemption from CIL covers an owner who lives in the house, claimed on its own form. If work starts before the council decides the claim, the claim lapses and the levy is due. Unlike the self-build and annex exemptions there is no clawback and no commencement notice is needed. Garden rooms and outbuildings count as floorspace if they are buildings people normally go into.

The levy applies to development permitted by the national order as well as by planning permission. The notice of chargeable development goes to the council. Whether anything is due depends on the new floorspace and on the building's use. The deduction for existing floorspace applies only where the building was in lawful use for a continuous six months in the three years before the development is permitted; a redundant farm building may not have been. In June 2026 the Valuation Office allowed no deduction at all for a barn regularised by a retrospective permission. The notice is easy to miss on permitted development, because a prior approval is not a planning application and may not prompt it. Schemes adding under 100 square metres and no new home need no such notice; nor do exempt home extensions.

The period runs for three years from the completion certificate. The exemption rests on the person who built or commissioned the home living in it as their sole or main residence. Selling it, letting the whole of it or it ceasing to be self-build housing within the three years ends the exemption; the person who had the exemption must tell the council within 14 days. In 2025 the High Court held that a sale before the home is finished counts too. The CIL exemption also needs a second form, with the evidence of completion and occupation, within six months of the completion certificate.

Where a council charges the levy, it helps fund general infrastructure such as roads, schools and open space; a section 106 covers affordable housing and needs specific to the site. Since 2019 both can fund the same item. CIL is a fixed charge per square metre set in advance, while a section 106 is negotiated for each scheme and an obligation can only count towards the permission where the scheme needs it. A scheme can pay both; the negotiation that matters on a section 106 is covered in the guide to section 106 agreements.

Both periods run from the date of the liability notice. Neither a review nor an appeal on the amount is possible once development has begun; an appeal lapses if work starts before it is decided. Surcharges are appealed separately, to the Planning Inspectorate. In 2026 the High Court refused to let a developer reopen floorspace it had not proved within those periods. The arguments that move a CIL amount are about floorspace, what counts as existing and whether a building was in lawful use for long enough, so the evidence belongs with the application.

The CIL exemption is for an owner who lives in the main house. It is claimed on its own form and needs a commencement notice before work starts. It can be clawed back for three years from the completion certificate if the annex is let, either is sold on its own or the house stops being a single dwelling. Accommodation that is not a separate dwelling and adds less than 100 square metres pays nothing in any case.

In November 2025 the government said it did not intend to commence it. Councils that charged CIL therefore went on doing so under the 2010 regulations; the rules on this page were those in force when it was checked. In June 2026 the government said it would consult on changes so that householders and self-builders are not charged because of procedural errors; no consultation had been published by mid-October 2026.