Certificate of appropriate alternative development

A certificate of appropriate alternative development is a formal statement by the local planning authority of what development, if any, would have been granted planning permission on a piece of land had it not been for the compulsory acquisition. It exists for one purpose: to fix the planning assumptions used when compensation is assessed. On a field with no allocation and no permission, the difference between a certificate saying nothing would have been permitted and one saying residential development would have been can be the difference between agricultural value and development value.

The certificate does not grant permission and it does not permit anything to be built. It answers a valuation question in planning terms.

What the certificate does and who applies

The scheme sits in the Land Compensation Act 1961. Either party directly concerned may apply: the claimant whose interest is being acquired, or the acquiring authority.

The application can be made where the land is subject to a compulsory purchase order, where a notice to treat has been served, where a general vesting declaration has been made, or where the interest is being acquired by agreement by a body with compulsory powers. That last case catches more landowners than expected, because a negotiated sale to an authority that could have used compulsion still qualifies.

The authority then issues a certificate stating either that there is development that would have been appropriate alternative development, describing it and any conditions it would have carried, or that there is no such development. Where it identifies development, it may also state the date on which permission could reasonably have been expected to be granted, which matters where the value depends on timing.

Its role in the compensation calculation

Compensation for compulsory acquisition is based on the open market value of the interest taken. Market value depends on what a purchaser could realistically do with the land, which depends on what permission could be obtained.

The Act directs that the scheme underlying the acquisition is disregarded. You value the land in the world where the road, the reservoir or the regeneration project was never proposed, which is where the difficulty lies, because that world has to be reconstructed rather than observed.

A certificate settles the planning half of that reconstruction. It does not settle value. The valuer still has to decide what a purchaser would pay for land with that planning prospect, applying a discount for the risk, the cost and the delay of actually obtaining permission.

The assumptions the authority must make

The authority decides the application as a planning question, not a valuation one. It asks what permission would have been granted on an application made on the relevant date, in the absence of the scheme.

That means working through the development plan as it stood, the national policy of the time, the site's constraints and the pattern of decisions in the area. Allocations matter. So do designations, access constraints, flood risk, heritage and highway capacity, because a certificate for housing on land with no achievable access is worth very little when a valuer tests it.

The authority may also grant a certificate for development different from the one applied for. An applicant seeking residential development may receive a certificate for employment use, which is a real outcome rather than a refusal.

Applying, and the information to provide

Make the application specific. A certificate application describing housing development is weaker than one describing a defined quantum of housing with an indicative layout, an access strategy and a note on how the constraints are dealt with.

Supply the evidence that an application would have carried. The development plan policies relied on, the constraints search, an access appraisal, and a short appraisal of technical matters such as drainage and ecology. A well-argued Planning Statement setting out the policy case does the work here, written as though the application were being made in the no-scheme world.

The authority has a set period to respond, extendable by agreement, and a failure to issue in time is treated in the same way as a decision you can take further. Keep the correspondence and diary the date.

Appealing a certificate

Appeals against a certificate, or against a failure to issue one, go to the Upper Tribunal, Lands Chamber, rather than to the Secretary of State. The time limit is short and it runs from the issue of the certificate or the expiry of the period for issuing it.

The Tribunal decides the planning question itself and may cancel the certificate and issue a different one. That is a full rehearing rather than a review of the authority's reasoning, so the evidence you put in matters more than the defects in the decision you are challenging.

Costs follow the Tribunal's own rules, and the compensation code makes provision for the claimant's reasonable expenses in some circumstances. Take advice on that before incurring them.

Timing against the compulsory purchase process

The certificate question tends to be left too late, usually because everyone is occupied with the order itself.

Start it once the acquisition is reasonably certain. Running the certificate application in parallel with the order process means the planning position is settled, or at least clearly in dispute, by the time compensation negotiations begin in earnest. Waiting until after vesting means arguing valuation and planning at the same moment, in front of people with different expertise.

Where the acquiring authority applies first, respond properly rather than ignoring it. A certificate issued on the authority's application binds the compensation assessment just as much as one you obtained.

Why the certificate can move the figure so far

Agricultural land with no development prospect is worth agricultural value. The same land with a certificate for residential development is worth something a great deal higher, discounted for risk and time but recognisably development land.

That gap is why the certificate is worth serious effort, and it is also why the law around it has been under review. The Levelling-up and Regeneration Act 2023 introduced powers allowing directions in certain compulsory purchase schemes, for purposes such as affordable housing, health and education, under which the value attributable to prospective planning permission may be disregarded. Whether such a direction applies to a particular order is a question to check at the time, because the position has been developing and is fact-specific.

Where the certificate identifies a use whose value turns on what the scheme could actually support, a Viability Assessment prepared to the relevant professional standard is the evidence a valuer will want alongside it. Councils usually expect a suitably qualified author for viability work and professional review is strongly advised.

Take proper advice early. This is one of the few parts of the planning system where a document obtained in the wrong order costs the applicant real money, and where the other side is a public body with its own valuers. Browse the supporting document types to see what evidence a certificate application should carry.

This is general guidance, not legal advice; compulsory purchase compensation is a specialist field and you should take advice from a qualified surveyor and solicitor before relying on any of it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.