Budgeting for CIL and the exemption paperwork
The levy is arithmetic, the exemption is administration, and it is the administration that goes wrong. How to budget for both, including the surcharge risk.
The Community Infrastructure Levy is the one cost on a self-build budget that can move from zero to five figures because of a missing form. The charge itself is arithmetic. The exemption is administrative, and it is the administration that goes wrong.
Budget for it in two parts. The potential charge, calculated from the charging schedule as if no relief applied, and the cost of the paperwork failing, which is a surcharge and, in the worst case, a bill you thought you had removed.
How the charge is calculated and when it falls due
The levy is charged per square metre of net additional gross internal floorspace, at the rate in the collecting authority's charging schedule for that zone and development type. Existing floorspace that has been in lawful use for a qualifying period can be deducted, which is why a conversion often carries a much smaller charge than a new build of the same size.
Rates are indexed annually. The index used is published each year and applied from 1 January, so a permission granted in December and one granted in January can carry different figures for identical schemes. Always work from the current schedule and the current index rather than a figure quoted to you a year ago, and take the method from the same source you use to work out liability from a charging schedule.
Liability crystallises on commencement, not on grant. That is the single most useful fact for cash flow planning. The authority issues a liability notice after permission, and a demand notice once development starts, and payment becomes due according to the authority's instalments policy if it has one.
Liability notices, assumption of liability and demand notices
Three documents move in sequence, and each has a response attached to it.
- The liability notice, issued by the collecting authority after permission is granted, setting out the chargeable amount.
- The assumption of liability form, submitted by whoever will pay, before development starts.
- The demand notice, issued after commencement, stating the amount and the payment dates.
Assumption of liability is easy to overlook because nothing appears to depend on it. It does. If nobody has assumed liability when development begins, liability defaults to the landowner and a surcharge applies for each owner, which is a small sum on its own and an irritating one to explain to a client.
Keep the correspondence. Authorities recalculate after a section 73 permission, and a client who has the original notices can challenge a revised figure far more easily than one who cannot find them.
The self-build exemption and the forms that secure it
The self-build exemption removes the charge for a dwelling built by, or commissioned by, someone who will occupy it as their principal residence. It comes in two stages and both are compulsory.
Part one of the self-build exemption claim goes in before development starts, and the authority must have granted it before you begin. Part two follows within six months of completion, with the supporting evidence the regulations specify, which in practice means proof of title, evidence of occupation such as council tax records, and a completion certificate or structural warranty.
The three-year clawback is where budgets get caught. Selling or letting the dwelling within three years of completion is a disqualifying event, and the full levy becomes payable. A self-builder planning to move within that window should budget for the charge rather than the exemption, because the money will be owed.
There is also a residential annexe exemption and a residential extension exemption, each with its own form and its own evidence. Minor development below the floorspace threshold generally falls outside the levy altogether, which is why most single-storey rear extensions never encounter it.
Commencement notices and the surcharge for missing one
Submit the commencement notice before you start, in writing, to the collecting authority, and keep proof of the date it was received.
Historically, failing to serve a commencement notice on an exempted self-build scheme removed the exemption outright, and a number of self-builders faced bills running into tens of thousands of pounds for a form that took ten minutes. Amendments made in 2019 changed that position, replacing the automatic loss of the exemption with a surcharge. The surcharge is calculated as a proportion of the notional chargeable amount subject to a cap, so it is a real cost rather than a nominal one.
Two practical points follow. Serve the notice even if you are certain the exemption is in place, and treat a site clearance or a foundation trench as commencement rather than assuming there is a grace period. Material operations are defined widely.
Where an authority takes the view that development started earlier than you say it did, it can determine a deemed commencement date, and there is an appeal route against that determination. Use it promptly, because the appeal windows are short.
Instalments, cash flow and what to hold back
A charging authority may publish an instalment policy allowing payment in tranches linked to elapsed time from commencement. Those policies vary widely and should be read before you fix the build programme, because bringing forward a start date can move a payment into a quarter when the money is not there.
Instalments are conditional. Miss a payment, or fail to serve the commencement notice, and the authority can withdraw the instalment arrangement and demand the full amount immediately. Late payment interest and, in serious cases, a stop notice follow.
Hold a contingency even on an exempt scheme. A modest reserve against a surcharge or a recalculated charge costs nothing if it is never spent, and the alternative is a stalled build.
Where an exemption is lost and cannot be recovered
Some errors are fixable and some are not, and knowing which is which changes how hard you chase the paperwork.
Generally not recoverable. Starting development before the exemption has been granted. Failing to submit part two within the deadline. A disqualifying event inside the clawback period.
Generally recoverable or reviewable. An arithmetical error in the chargeable amount, which can be reviewed and then appealed. A surcharge imposed where you did in fact serve the notice, if you have proof of service. A deemed commencement date you can rebut with dated site evidence.
Photograph the site the week before you start and keep the timestamps. It sounds excessive until an authority asserts a commencement date three months earlier than yours.
Building the levy into the project budget
Treat the levy as a line item with three components. The calculated charge at the current index, the professional time to prepare the claim and assemble the evidence, and a contingency for surcharge risk.
Do that at feasibility rather than after permission. A charge that makes a plot marginal is better discovered before the land is bought, and the calculation needs only the charging schedule, the proposed floor area and the deductible existing floorspace. The comparison with other upfront outgoings, including the application fee itself, is set out in the note on Building Regulations fees against planning fees.
The levy sits alongside the documents the application itself needs, and a planning statement is usually where the self-build intention is first recorded. If you want to see what the total documentation spend looks like before committing, the pricing page sets out the options.
This is general guidance, not legal advice. Levy rates, indexation, forms and deadlines change, so check the current charging schedule and the current regulations with your collecting authority or a qualified professional before relying on any figure here.
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Frequently asked questions
When does CIL actually become payable?
Liability crystallises on commencement rather than on grant of permission. The authority issues a liability notice after permission and a demand notice once development starts, with payment dates set by its instalment policy where it has one. That gap between grant and commencement is the window in which exemption paperwork has to be completed.
What happens if I forget the commencement notice?
Historically the self-build exemption was lost outright, which produced some very large bills. Amendments made in 2019 replaced that automatic loss with a surcharge calculated as a proportion of the notional chargeable amount, subject to a cap. It is still a real cost, so serve the notice in writing and keep proof of the date it was received.
Can I sell a self-build house after claiming the exemption?
Not within the clawback period without consequences. Selling or letting the dwelling within three years of completion is a disqualifying event and the full levy becomes payable. If a move inside that window is likely, budget for the charge rather than the exemption, because the money will be owed whatever the original claim said.
Do extensions attract the levy?
Most do not. Minor development below the floorspace threshold generally falls outside the levy, which is why typical single-storey rear extensions never encounter it. Larger extensions to a dwelling that remains the owner's principal residence can claim a residential extension exemption, which has its own form and its own evidence requirements.
Can I challenge the amount the council has calculated?
Yes. There is a review procedure for the chargeable amount and appeal routes covering surcharges and deemed commencement dates. The windows are short, so act quickly and keep the original liability notice. Arithmetical errors and wrongly applied surcharges are the most commonly successful challenges, particularly where you hold proof of service.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.