CIL Charging Schedule A Developer's Guide to UK Levy Risk

A deal can look clean right up to the point when CIL stops being a planning note and turns into a funding problem.

You agree a land price. The appraisal clears committee. Debt terms look workable. Then the detailed review starts and someone realises the assumed levy was based on an old rate, the wrong charging zone, or the wrong index year. Suddenly the liability notice is materially above the appraisal line. Nothing about the scheme has changed physically, but the margin has narrowed and the peak debt curve has moved in the wrong direction.

That’s why a cil charging schedule deserves the same attention as build cost inflation, sales absorption, and finance assumptions. Treat it as a static cost and you’ll underwrite false comfort. Treat it as a live variable tied to authority, use class, timing, phasing, and instalment rules, and you can usually see the risk early enough to price it properly.

Developers get caught here for a simple reason. CIL looks deceptively tidy on paper. In practice, it’s a local tax system with enough variation between councils to distort residuals, cashflow timing, and lender confidence if you model it lazily.

The CIL Surprise That Can Derail Your Development

The common mistake is assuming CIL is just rate times area.

On a live scheme, the pain usually comes from the details around that calculation. A team pulls a rate from a council website, applies it to a broad GIA assumption, and moves on. Months later, planning is granted, the levy is indexed, the floorspace measurement tightens up, and the instalment policy turns out to be less forgiving than expected. The result isn’t academic. It shows up in equity need, debt draw profile, and land value.

I’ve seen this happen most often on schemes where the development team is moving quickly and nobody owns the CIL workstream properly. Planning assumes finance has covered it. Finance assumes planning has checked the schedule. Lawyers only come in once documents are already in motion. By then, the wrong assumption has usually spread through the whole model.

Practical rule: If your appraisal only contains one CIL input cell, you probably haven’t modelled CIL risk. You’ve only estimated a placeholder.

The headache gets worse on phased sites and London deals. Some sites carry both local authority CIL and Mayoral CIL. Some authorities are relatively straightforward on timing. Others create a cashflow profile that can shift a scheme from manageable to awkward, even where the total levy is unchanged.

The main issue is not whether CIL exists. It’s whether your underwriting reflects how the relevant authority applies it. That means checking the charging schedule, adoption date, indexation basis, zone mapping, use category, instalment policy, and any relief process before your land bid hardens into commitment.

What Is a CIL Charging Schedule

A site goes into appraisal at one rate, then the planning team discovers the council charges different amounts by zone, applies indexation from an older base year, and expects payment on a timetable that does not match the debt model. That usually starts with one missed document. The charging schedule.

A cil charging schedule is the adopted council document that sets the levy rates for different types of development in that authority. It usually splits charges by use, and often by geographic zone, so it is more than a headline £ per sqm figure. It is the document your surveyor, planner, and finance team should all be using when they decide whether a scheme still works.

Unlike section 106, CIL is generally applied through a published tariff rather than argued line by line for each site. That distinction matters in underwriting. A section 106 package may still move through negotiation and viability discussion. A CIL rate in an adopted schedule is usually fixed unless a relief, exemption, or procedural error changes the outcome. If you need the contrast set out clearly, this guide to section 106 agreements gives the legal context.

The document you underwrite from

Developers sometimes treat the charging schedule as a planning attachment. It is closer to a pricing document with legal force.

The schedule tells you four things that affect value immediately. Which uses are charged. Where different zones apply. What the adopted rates are. Which charging document is in force for the relevant permission. If any one of those points is wrong in the appraisal, the error usually flows straight into land value, equity requirement, and debt sizing.

The adoption date also matters because it ties back to indexation. On a live deal, that is not a technical footnote. It affects the amount payable, especially where the rate was adopted years earlier and build cost inflation has moved on. The schedule also works alongside other authority documents, such as the instalments policy and guidance notes, so reading only the rate table is not enough.

A charging schedule is policy, but it behaves like a cost input

Councils prepare charging schedules through consultation, viability testing, examination, and adoption. In practice, that means the document can sit in draft for a long time, then change shortly before your application or permission. The Ministry of Housing, Communities and Local Government examined how CIL was introduced and operated across authorities in its research on the Community Infrastructure Levy. For deal teams, the lesson is simple. Do not assume the current adopted rate is the only rate that matters if a review is already in motion.

You see this in live authorities. Arun’s schedule took effect in April 2020. Vale of White Horse adopted a revised schedule in October 2021, effective from November 2021. Oxford City has consulted on a draft schedule linked to its emerging Local Plan 2040. Those are not abstract planning milestones. If you are pricing land while a revised schedule is being examined or consulted on, you need to test the downside case before the bid hardens.

What the schedule does not tell you on its own

A charging schedule does not give you the final CIL figure by itself. It gives you the rate framework. You still need to apply the right measurement basis, confirm any existing floorspace credit, check whether multiple charging authorities apply, and deal with indexation correctly.

That is where teams get caught out. They read the schedule once, lift the headline rate, and move on. A better process is to treat the schedule as the starting point for a liability build-up, not the answer. On mixed-use or phased schemes, that distinction saves a lot of pain later.

Lenders care for the same reason. A CIL assumption backed by the actual charging schedule, with the correct zone and adoption basis, is underwritable. A single allowance with no audit trail is not.

How Councils Set and Vary CIL Rates

You agree a land price on a residential-led scheme. The appraisal carries a single CIL allowance lifted from an older deal in the same authority. Two weeks later, planning counsel checks the map and the proposed mix against the adopted schedule. The site sits in a higher charging zone, the commercial element falls into a pricier category than the team assumed, and the council has already signalled where it thinks updated viability evidence points. That is how CIL stops being a policy footnote and starts cutting straight into residual land value.

Councils set CIL rates through a viability judgement, not a generic tariff exercise. They look at infrastructure funding needs, test what different forms of development can bear, and then draw lines by geography and use. For underwriting, the point is simple. The charging schedule is the council’s published view on where development value sits and how much of it can be taken without stalling delivery.

Zoning changes everything

Geography is usually the first place rates split. Many authorities divide their area into charging zones, and that can create a meaningful pricing gap between sites that look similar at headline level. A town centre site, an urban extension, and a lower-value peripheral location may all sit under the same council but carry different CIL assumptions.

That creates very practical problems on live deals. Site finders often identify the right authority but stop short of checking the adopted zone map against the red line boundary. On edge-of-settlement sites, regeneration sites with awkward parcels, or schemes near borough boundaries, that shortcut can contaminate the appraisal early and stay unnoticed until the liability notice arrives.

A proper review checks four things before the land bid firms up:

• The charging authority: Especially where county, district, borough, and mayoral roles are easy to confuse
• The adopted zone map: The map matters as much as the text
• The intended use across the scheme: Rates often move sharply between residential, retail, office, industrial, and specialist uses
• Whether more than one CIL charge applies: A live issue in parts of London

The trade-off is obvious. Councils use zoning to reflect local value differences. Developers then inherit the mapping risk. If the boundary call is wrong, the appraisal is wrong.

Use classes show where the council thinks value exists

Use-based differentiation matters just as much. Councils charge more where they believe a use can carry the levy and less where viability is thinner or where they want to avoid choking off supply. That is not abstract policy. It affects whether a mixed-use layout still works after the commercial content, affordable housing, and abnormal costs have all been priced properly.

Oxford City Council’s August 2025 charging schedule revision was a good example. The revised approach showed how an authority can increase rates for stronger commercial uses while holding others where viability evidence is tighter. You see the same principle across many authorities. Councils do not set one universal rate because they are making different judgements about offices, labs, industrial, student housing, retail, and residential development.

That matters on schemes where the use mix is still moving. A design change from industrial floorspace to higher-value employment space may improve gross development value and increase CIL at the same time. Sometimes the extra value covers it comfortably. Sometimes it does not, especially once section 106, fit-out assumptions, and letting risk are added back in.

CIL rates are a viability signal from the authority. Read them that way, and the schedule becomes more useful for underwriting.

A short explainer on the broader CIL framework can help anchor the policy context before you look at local schedules:

London adds another layer

London often creates a second problem. Local authority CIL may sit on top of Mayoral CIL, so the issue is not just the rate in the borough schedule. It is the combined charge and the timing of payment against a scheme that may already be carrying heavy abnormal costs, tighter debt terms, and slower planning programmes.

Wandsworth is a familiar example because teams regularly focus on the borough figure and understate the total levy burden once the mayoral charge is added. On paper, that can look manageable. In the appraisal, it can narrow the margin on land value, reduce contingency headroom, and leave very little room for bad news elsewhere in the cost plan.

What experienced deal teams do differently

The better approach is to treat each charging schedule as an underwriting input, not background reading. Review the adopted rates, the zone maps, the use categories, and any draft revisions already in motion. Then test the scheme against realistic alternatives if the design, tenure mix, or use mix is still evolving.

What fails in practice is reusing a historic CIL allowance from another site and assuming the same borough means the same answer. It rarely does. Different zone, different use, different schedule, different outcome. On thin-margin deals, that is enough to turn an apparently workable bid into a problem job before planning is even submitted.

Calculating Your CIL Liability A Worked Example

A CIL appraisal usually looks tidy right up to the point someone checks the floorspace, the charging zone, and the index year. Then the number moves, sometimes by enough to spoil the residual or force a retrade on land.

Start with the authority formula

The core method is simple. Start with the adopted rate, apply it to the chargeable floorspace, then index it by the authority’s published basis for the charge year against the base year in the charging schedule.

On paper, that sounds mechanical. In live deals, the disputes sit inside the inputs.

A sound workflow looks like this:

1. Confirm the chargeable gross internal area
2. Confirm the correct use and charging zone
3. Apply the relevant indexed rate
4. Adjust for deductible existing floorspace, where it qualifies
5. Check whether relief, exemption, or procedural failure changes the outcome

The formula is rarely the problem. The assumptions are.

A practical worked example

Take a small residential scheme with proposed new build floorspace and some existing built area on site. The appraisal team needs one answer, but there are really four separate judgements underneath it.

First, establish the proposed gross internal area that falls within CIL. Do not use a sales area schedule or an early planning sketch and assume it is close enough. If the architect, QS, planner, and finance model each carry a different area figure, the CIL line will drift before anyone notices.

Second, test whether any existing floorspace can be deducted. Many appraisals falter at this point. Retained structures, partial demolition, and rebuild strategies can all change the net chargeable position, but only if the existing area qualifies under the rules and the evidence is there.

Third, confirm the charging zone and use category from the adopted schedule and maps. I have seen schemes underwritten on the wrong zone because someone relied on an old site note from another instruction in the same borough. That is an avoidable mistake, and it can be expensive.

Fourth, apply the correct indexation basis. As noted earlier, councils publish annual indexed rates or the figures needed to derive them. If the base year in the schedule is picked up incorrectly, the maths still works but the liability is wrong.

What the numbers look like in practice

Assume an authority has an adopted residential rate of R per square metre. Assume the scheme proposes 1,200 sq m GIA and has 300 sq m of deductible existing floorspace that properly qualifies. The starting chargeable area is 900 sq m.

The unindexed liability is:

900 × R

If the charge year index is higher than the base year index in the adopted schedule, the indexed rate increases accordingly. The calculation becomes:

900 × R × (charge year index / base year index)

That step is where land bids get caught out. A rate that looked manageable in the first residual can move enough to cut land value, reduce debt headroom, or push the developer’s profit below target.

Then check whether any relief is available and whether the paperwork can be done in time. Relief that is available in theory but missed in procedure is worth nothing. For custom build and small residential projects, the rules around a CIL self build exemption are a good example of how eligibility and process have to line up.

The floor area issue that causes real friction

Chargeable area is where finance assumptions and project delivery often part company.

Early appraisals may use broad conversion ratios from NIA to GIA or a planning massing estimate. That is acceptable for a first sensitivity test. It is not good enough for committee approval, debt draw assumptions, or a fixed land position. CIL is sensitive to floorspace definitions, demolition assumptions, and what is retained on site.

One late design revision can do the damage. Add plant space, alter circulation, increase core area, or change the mix of ancillary accommodation, and the chargeable GIA can shift without anyone revisiting the levy line. The result is a model that looks consistent and a cash requirement that is not.

Underwriting note: Hold one approved chargeable area assumption in the appraisal, and require a specific CIL check every time the design team issues a revised area schedule.

What a usable worked appraisal file should contain

A credible CIL calculation file should show:

• The adopted charging schedule used
• The site’s charging zone and map reference
• The use class or charging category applied
• The proposed and deductible existing GIA assumptions
• The indexation basis used for the appraisal
• Any relief or exemption being relied on
• Any procedural deadlines that could invalidate that position

If those points are missing, the CIL number is still provisional, whatever the spreadsheet says.

Managing Cashflow Instalments Reliefs and Exemptions

A scheme can be fully funded on paper and still hit a cash squeeze because CIL falls due earlier than the team expected. I have seen that happen where the appraisal carried the right total levy but the wrong payment profile. Debt was sized to the headline cost. The authority’s instalment policy then pulled cash into the early works period, right when groundworks, utilities, and contractor preliminaries were already loading the curve.

That is the practical problem. CIL is not only a cost item. It is a timing risk.

Why instalment policy matters to underwriting

Two authorities can produce a similar overall liability and very different funding pressure. The difference sits in their instalment policies.

The Greater London Authority 2024 schedule is relatively front-loaded. For liabilities over £100,001, it requires 50% within 60 days and the balance within 240 days, as set out in the Greater London Authority charging schedule. Other councils allow a longer spread over more stages. On a larger scheme, that can materially reduce peak debt and defer part of the equity requirement.

For a £1.5m liability, the shape of the cash call matters as much as the amount.

Payment Due Date	Greater London Authority (2-Stage)	Longer 4-Stage Council Profile
60 days	£750,000
90 days		£375,000
240 days	£750,000	£375,000
450 days		£375,000
720 days		£375,000

A front-loaded profile pulls cash into the least forgiving part of the programme. Sales receipts are usually not there yet. Refinancing options may still be limited. If the facility was not structured with that profile in mind, the team ends up solving a treasury problem rather than a planning one.

What to model, not just what to total

The right appraisal test is simple. Map CIL to the actual instalment policy adopted by the charging authority and place each payment against the current programme.

Do not spread it monthly for convenience. Do not drop it into one generic quarter-end line. Both shortcuts flatten the actual risk and understate peak funding pressure.

On phased sites, test the administrative point as well as the cashflow point. A council may treat phases in a way that changes when liability crystallises, and where Mayoral CIL sits on top of borough CIL the interaction can become messy quickly.

Reliefs and exemptions only work if the process is clean

Relief is valuable. Lost relief is expensive.

The problem is usually procedural rather than technical. Teams identify a qualifying route, then miss a notice, start works too early, or leave responsibility split between planning, legal, and project delivery. Once that happens, the appraisal still shows the saving but the live scheme does not get it.

Screen for the obvious items early:

• Social housing relief, where the consented affordable mix may qualify
• Charitable relief, if ownership and use meet the tests
• Self build routes, which come up regularly on smaller residential schemes. The process issues are set out in this guide to the CIL self build exemption
• Small balance treatment, where some authorities disregard very low liabilities under their local arrangements

Those checks belong in the development control process, not as an afterthought once permission is issued.

What works in practice

Give one named person ownership of CIL administration. That person should track assumption of liability forms, commencement notices, relief applications, and any evidence needed to keep an exemption alive after start on site.

Then do four things consistently:

• Model the authority’s actual instalment policy
• Link commencement approvals to notice compliance
• Keep total liability separate from payment timing in the cashflow
• Review relief conditions again before any site start

That discipline avoids a common failure mode. The legal documents are in order, the build contract is ready, the lender is comfortable with total cost, and then a notice error or compressed instalment profile creates an avoidable cash call. On a thin-margin deal, that is enough to erode contingency or force a last-minute equity top-up.

Modelling CIL Risk in Your Development Appraisal

By the time a credit paper reaches approval, CIL should no longer be a guessed line item. It should be a tested risk assumption with an evidence trail.

The appraisal job is not merely to estimate one levy figure. It is to understand how CIL behaves under different timings, designs, and authorities, then show what that does to land value, peak debt, and downside protection.

Build three cases, not one

A strong model usually carries at least three CIL positions.

• Base case: Current schedule, current known zone, current assumed chargeable area
• Timing risk case: Same scheme, but with forward indexation and a later permission date
• Policy stress case: Revised schedule exposure, different instalment outcome, or a tighter interpretation of phase treatment

In this context, a formal sensitivity analysis in development appraisal becomes useful. CIL shouldn’t sit outside that exercise. It should sit inside it, alongside build costs, sales values, programme, and finance costs.

Where most models go wrong

Most weak appraisals fail on one of four points.

First, they assume current rates remain static until permission. That is dangerous on longer dated planning routes.

Second, they treat the levy as a single draw in the cashflow, ignoring authority specific instalment schedules.

Third, they don’t lock floor area assumptions properly. So the planning set, architect set, and finance set all drift apart.

Fourth, they ignore phased development complexity. Verified guidance highlights that Newham’s 2026 updates and Wandsworth’s policies expose a real challenge in modelling phased developments where both local and Mayoral CIL apply, while GOV.UK guidance lacks borough specific tools for that aggregation, as discussed in Wandsworth’s CIL charging schedule and related policies.

That last point is especially important on large sites. If phase level CIL isn’t modelled cleanly, the scheme can appear financeable in the headline appraisal while carrying hidden short term funding spikes.

A lender’s view of good evidence

Credit teams usually want to see that the borrower has done more than pull a headline rate. A strong underwriting pack tends to include:

Appraisal item	What good looks like
Charging basis	Adopted schedule identified and dated
Location evidence	Site matched to the correct charging zone
Use evidence	Proposed use mapped to the relevant charging category
Timing	Permission timing and index exposure considered
Cashflow	Instalments modelled on actual authority policy
Phasing	Separate treatment where phases trigger separate levy events
Procedure	Relief opportunities and notice requirements flagged

The practical test

Ask a blunt question. If planning consent lands later than expected, can your model still explain what happens to levy, cash, and land value without rebuilding the whole file?

If the answer is no, your CIL treatment is too thin.

Good underwriting doesn’t remove CIL risk. It makes the risk visible early enough to price, negotiate, or walk away.

That is the core purpose of modelling. Not precision for its own sake, but decision quality.

Your CIL Due Diligence Checklist

Every site file needs a CIL checklist before land is exchanged, before credit signs off, and before any commencement step is taken. The aim isn’t to make CIL simple. It isn’t simple. The aim is to stop it being a hidden variable.

What to verify before you commit

Run through these points in order.

• Confirm the charging authority: Don’t assume the planning authority, collecting authority, and any wider London levy position have all been captured correctly.
• Download the live charging schedule and related policies: Keep the exact documents used in the deal file, not just screenshots or copied rates.
• Check historic and emerging schedules: A live draft revision can matter if your permission timetable is long.
• Pin the site to the correct zone map: This should be done visually, not by postcode shorthand.
• Match every use to the authority’s charging category: Mixed use schemes need use by use treatment.
• Identify the effective date and index basis: If the schedule has been in force for some time, stale index assumptions can distort the appraisal.
• Review instalment policy in full: Lenders care about when cash leaves, not just how much.
• Screen for dual levy exposure: Particularly on London sites.
• Check whether phase treatment alters liability timing: Large schemes often fail here.
• Review relief and exemption routes early: Some opportunities disappear if the process is mishandled.
• Align measured floorspace across teams: Planning, architecture, QS, and finance should all be working from the same basis.

Questions to ask your advisers

Your planning consultant, solicitor, and development manager shouldn’t all answer the same question in isolation. Force a joined up review.

Ask:

1. Has anyone checked whether a revised charging schedule could apply before permission is granted?
2. Is the site definitely in the mapped zone assumed in the appraisal?
3. Do the measured areas used for CIL match the latest scheme drawings?
4. Does the authority instalment policy create a short term funding pinch?
5. Are there reliefs we may qualify for, and who owns the filing process?
6. If the scheme is phased, have local and mayoral levy interactions been mapped properly?

The standard worth adopting

The best internal standard is simple. No site goes unconditional with an unreferenced CIL assumption. No lender pack goes out without documentary support for the levy line. No commencement happens without someone checking the procedural chain.

That won’t make CIL pleasant. It will make it manageable.

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Domus helps UK development and lending teams turn CIL from a spreadsheet afterthought into an auditable part of viability, planning, and finance workflow. If you want a cleaner way to model levy assumptions, stress test cashflow, and produce lender ready appraisal evidence, take a look at Domus.