Cascade clauses when no provider takes the units

A cascade clause is the part of a section 106 affordable housing schedule that says what happens if no registered provider will take the units. It sets out a marketing exercise, then an alternative tenure, then usually a commuted payment, in a defined order with defined timescales. Without one, a scheme where no provider bids is stuck: the obligation requires transfer to a registered provider, no provider will contract, and the market units cannot be occupied because the trigger has not been met.

Authorities dislike cascades because they can look like a route out of the affordable housing requirement. The way to get one agreed is to make the marketing obligation hard rather than soft, and to let the authority control the price point.

Why no provider bids

The reasons are predictable, and understanding them is what lets a developer design the problem out rather than drafting around it.

Small numbers of scattered units in a market scheme are expensive to manage. Flats with high service charges and a share of a lift, a sprinkler system or a communal plant room can be unlettable at a social rent once the charge is factored in. Tenure mixes that no longer match the provider's stock strategy get declined. Units that fail the provider's own employer's requirements, on space standards, accessibility, acoustic separation or metering, get declined on quality grounds. And where grant is not available for the tenure the policy requires, the numbers do not work however good the units are.

Geography matters too. A provider with no existing stock within a reasonable management radius will usually refuse a handful of units, whatever the price.

The practical lesson is that provider engagement belongs before the application, not after the permission. A letter of intent from a provider, obtained at pre-application stage, removes most of the argument about whether a cascade is needed at all. Where the units have been designed to a provider's standards from the outset, as covered in space standards and accessible housing as appraisal inputs, the refusal risk falls sharply.

The marketing obligation

This is the limb that decides whether an authority will accept the clause. A weak marketing obligation is the reason most draft cascades are rejected.

A workable obligation specifies six things.

1. Who must be approached: commonly every registered provider on a list agreed with the authority, or all providers with stock in the district, with a minimum number of approaches.
2. What must be offered: the units, their tenure, their specification and the transfer terms, in particulars approved by the authority before issue.
3. At what price: by formula or by independent determination, not at the developer's discretion.
4. For how long: commonly six months from the date the particulars are issued, with a longer period where the units are not yet built.
5. What evidence must be produced: copies of the particulars, the distribution list, every response received, and a statement from the developer.
6. Who verifies it: the authority, with a defined period to accept or dispute the evidence.

The price point is the crux. If the developer can set the transfer price, the cascade can be triggered at will, and no authority should accept that. The two standard answers are a formula tied to a stated percentage of open market value for each tenure, or a determination by an independent valuer appointed jointly, with the valuer instructed to assess the price a reasonable provider would pay. The second is slower and much harder to challenge.

The tenure cascade

Where marketing fails, the obligation steps down through alternative tenures before reaching money. The order reflects the authority's policy preference, with the most policy-compliant option first.

Each step needs its own marketing period, or the cascade takes years. The usual compromise is a full period at step 1 and shorter periods, often three months, at each subsequent step, with the authority able to waive a step in writing if it accepts that step is futile.

Note: a cascade that reaches step 4 or 5 changes the scheme's compliance position, so the planning balance that justified the permission has to still hold. Where the original consent was granted on a policy-compliant offer, an authority will want the agreement to say that the fallback does not reopen the viability position.

The commuted payment

The final step is a payment calculated to let the authority deliver equivalent provision elsewhere, and the calculation has to be in the agreement rather than left to later negotiation.

Two approaches are common. The first is the difference between the open market value of the units and the transfer value that the affordable tenure would have produced, which captures the developer's gain. The second is a formula in the authority's own affordable housing supplementary planning document, usually expressed per unit or per square metre and index-linked.

Three details are worth insisting on. The payment should be index-linked from the date of the agreement to the date of payment, using a named index. The trigger should be tied to a measurable event, usually occupation of a stated proportion of the market units, not to practical completion. And there should be a provision dealing with what happens if a provider emerges after the payment has been made, which is rare but awkward where it happens.

An illustrative example

This example is illustrative. A 26-unit scheme in a town centre includes 8 affordable units in a flatted block with a lift and a communal heating system. The policy tenure is social rent. Eleven registered providers are approached with particulars approved by the authority, at a price determined by an independent valuer. Nine do not respond, two decline citing the service charge exposure. At step 2 the units are offered at affordable rent with a service charge cap, and one provider accepts six of the eight. The remaining two convert to shared ownership at step 3 and are taken by the same provider. No commuted payment arises. The marketing evidence file runs to forty pages and the authority accepts it in three weeks.

Evidence of refusal, and what authorities look for

An authority assessing marketing evidence is asking one question: was this a real attempt?

What satisfies: particulars that describe the units accurately and attractively, a distribution list including providers active in the district, a price supported by independent valuation, written responses from providers giving reasons, and a timeline showing the marketing ran for the full period at the right time of year rather than over Christmas.

What does not satisfy: a single email to a handful of addresses, particulars that omit the service charge or the specification, a transfer price asserted by the developer, and an evidence file with no responses in it. An authority faced with that will refuse to certify the step, and the cascade does not advance.

Where the underlying problem is that the scheme cannot carry the policy requirement at all, the cascade is the wrong instrument and a viability case is the right one. That runs through a Viability Assessment and an independent review, which we cover in independent review of a viability appraisal. Conflating the two, by using a cascade to achieve a viability outcome, is what makes authorities suspicious of cascades in the first place.

Drafting the authority will accept

Offer the hard version first. A cascade with an approved particulars requirement, an independently determined price, a full marketing period and a verification step is more likely to be agreed in one round than a soft version negotiated down over three.

Two additions help. A long-stop date, after which the authority may direct which step applies, stops units sitting empty while the cascade grinds. And a reporting obligation, requiring the developer to notify the authority at the start and end of each step, keeps the process visible rather than reconstructed afterwards.

Set out the proposed mechanism in the Affordable Housing Statement at application stage, with the heads of terms, so the authority's housing officer sees it before the legal team does. Enter your postcode on PlanScope to see which reports your scheme is likely to need.

This is general guidance, not legal advice. Section 106 drafting should be settled by a solicitor acting for you, and the authority's own model agreement and affordable housing guidance will govern. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.