Reading a council's housing land supply monitoring

A council's housing land supply position is an arithmetic statement dressed as a policy document, and most of the argument about it happens in the assumptions rather than the total. Housing land supply data is published, it is checkable, and a consultant who reads it carefully can usually identify within an afternoon whether the authority's claimed position holds up.

The work is worth doing before you commit to an appeal strategy, because the answer determines which balance the inspector will apply.

Where the figures are published

Three documents carry the position, and they do not always agree with each other.

The first is the authority's published housing land supply statement, sometimes issued annually and sometimes only when challenged. It sets the base date, the requirement, the buffer and the supply, and it lists the sites relied on.

The second is the authority monitoring report, which reports completions, permissions and progress on plan preparation. It is often the only place where past delivery is tabulated consistently.

The third is the land availability assessment, which sits in the plan evidence base and assesses sites for suitability, availability and achievability. It is where the assumptions about individual sites originate, and it usually predates the supply statement.

Where the three conflict, the conflict itself is the argument. An authority relying on a site in its supply statement that its own land availability assessment records as constrained has a problem it will have to explain.

Related guidance on locating these documents and the delivery test results is in finding housing land supply and delivery test figures.

Base date, requirement and buffer

Start with the base date, because everything else is measured from it. A supply statement with a base date 18 months old is describing a position that has moved, and completions since then change the arithmetic in both directions.

The requirement is the annual figure the supply is measured against. Check whether it comes from an adopted plan or from the standard method for calculating local housing need, and check which version of the method was applied, since the calculation has been revised. The derivation is explained in the standard method for calculating local housing need.

Then check the buffer. National policy applies a buffer to the requirement, with a larger buffer where past delivery has fallen short under the Housing Delivery Test. The test results and their consequences are set out in housing delivery test results and what they change.

Two errors recur. Applying the buffer to the wrong base, and carrying forward or ignoring a shortfall from earlier years without saying which approach has been used. Both change the requirement materially, and both are visible in the arithmetic if the statement shows its working. Where it does not, ask for it.

Testing whether a site counts as deliverable

Supply is made up of sites the authority considers deliverable within five years, and the Framework defines deliverability with a set of expectations about evidence. Sites with detailed permission for major development are generally treated as deliverable unless there is clear evidence otherwise. Sites without detailed permission, including allocations and outline permissions, need clear evidence that homes will be delivered within five years.

Work through the site schedule and sort it into categories.

1. Sites with detailed permission and visible activity, which are hard to challenge.
2. Sites with detailed permission but no activity, where lapse risk and developer intent are questions.
3. Sites with outline permission only, where reserved matters, conditions and infrastructure all sit ahead of delivery.
4. Allocations without permission, which need the clearest evidence and often have the least.
5. Large sites with build-out rates that assume more than one outlet operating at once.

Then test the trajectory. A site assumed to deliver 80 homes a year from a single outlet is making a claim about build rates that can be compared against what that developer has achieved elsewhere. A large site assumed to start delivering in year two, where the section 106 is unsigned and the access has no consent, is making a claim about programme.

The evidence that persuades an inspector is specific and dated: a letter from the site promoter, a lapsed permission, an unsigned agreement, an unresolved highway objection. General scepticism does not.

Lapse rates and windfall allowances

Lapse rates account for permissions that are never implemented. Some authorities apply one, some do not, and some apply it only to small sites. Where no lapse rate is applied at all, ask why, because permissions do lapse.

Windfall allowances cover sites that come forward unexpectedly and are not identified in the plan. National policy allows a windfall allowance where there is compelling evidence that such sites will consistently become available, and the allowance cannot include residential gardens in the usual case.

Check three things about a windfall allowance. Whether the evidence base for it is historic completions or an assumption. Whether it double counts sites already identified individually in the supply. And whether the trend it relies on predates a change that would affect it, such as the withdrawal of a permitted development right or the making of an Article 4 direction. The mechanics are covered in how councils count windfall sites.

Building your own position

Once you have tested the schedule, produce your own calculation rather than simply criticising the council's. An inspector will want a figure to compare.

Set it out in the same structure the authority used, so the differences are visible line by line. State the base date you are using, the requirement and its source, the buffer and its justification, the supply site by site, and the sites you have removed or reduced with a reason for each. Then state your resulting years of supply.

Be proportionate. Removing every site with an unsigned agreement produces a number nobody believes. Removing four large sites with specific, evidenced problems produces a number an inspector can adopt.

Record the date of every source you relied on and keep copies, because authorities update their pages and a link that worked when you wrote the statement may not work when the appeal is heard.

Using the figures in the balance

Where supply falls below the policy requirement, the relevant policies for the supply of housing are treated as out of date and the balance in national policy applies, subject to the protections the Framework retains for designated areas and other specified matters. Cite the current edition of the Framework, published 17 August 2026, and use its policy coding rather than paragraph numbers from earlier editions.

Put the arithmetic in the Planning Statement as a table, with the narrative underneath. Officers and inspectors read a lot of supply arguments, and the ones that land are the ones where the disagreement can be seen at a glance.

How quickly the position changes

Supply positions move. A plan adopted during an appeal, a new base date, a delivery test result, a large permission granted or a large site lapsing can all change the answer between submission and decision.

Recheck the position before the appeal statement is submitted, and again before any hearing. Where the position has changed against you, say so and deal with it rather than leaving the council to point it out. An advocate who updates their own figures keeps the credibility they need for the rest of the case.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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