Statements of common ground and the duty to cooperate

A statement of common ground is the document two or more authorities sign to record what they agree about cross-boundary planning matters, and it is the main evidence that the duty to cooperate has been met. Section 33A of the Planning and Compulsory Purchase Act 2004 requires authorities and prescribed bodies to engage constructively, actively and on an ongoing basis on strategic matters. A statement of common ground planning authorities produce for examination is how that engagement is demonstrated, and its absence or weakness has stopped more local plans than any soundness point.

What the duty to cooperate requires

The duty is a duty of process, not of outcome. It does not require authorities to agree, and it does not require one council to take another's housing.

What it requires is engagement that is constructive, active and ongoing, on the preparation of development plan documents and on activities that prepare the way for them, in relation to strategic matters. Strategic matters are those with a significant impact on at least two areas: housing and employment need, infrastructure, Green Belt, minerals and waste, flood risk and habitats mitigation among them.

Prescribed bodies are drawn in alongside the authorities. That list includes the Environment Agency, Historic England, Natural England, the highway authority, National Highways, the integrated care board and the Mayor of London where relevant. Engagement with a prescribed body counts, and councils frequently under-evidence it.

The duty applies from the beginning of plan preparation. Evidence of discussion in the final six months does not cure two years of silence, and inspectors say so.

Statements of common ground and their content

National policy expects authorities to prepare, maintain and update a statement of common ground documenting the cross-boundary matters being addressed and the progress in cooperating to address them.

A usable statement contains the signatories and the geography covered, the strategic matters in scope, what is agreed on each, what is not agreed and why, the governance arrangements for continuing work, and the timetable. The useful ones name figures. The weak ones describe meetings.

Three things make a statement credible to an inspector: dated signatures from each body rather than an officer-level note, explicit disagreement where it exists, and a mechanism for revisiting the position when circumstances change. A statement recording unanimous agreement on every point usually means the hard questions were avoided.

Cross boundary housing and employment need

Housing is where most of the work happens. The standard method produces a local housing need figure for each authority, and the question is whether each can accommodate its own.

Where one cannot, the shortfall becomes unmet need and the statement has to record whether neighbouring authorities will take any of it. Employment land raises the same question in a different form, usually around strategic distribution and warehousing where a site serves a wider market than the district it sits in.

Expect the statement to deal with the evidence as well as the conclusion: which housing market area and functional economic market area were used, which authorities are in them, and why. Boundaries drawn to exclude an inconvenient neighbour are the first thing an objector tests.

Our note on housing land supply and what it changes for applicants covers what happens on the application side when those plan-level figures are not met.

Unmet need and how it is distributed

There is no mechanism to compel an authority to accept another's unmet need. That is the structural weakness of the system and everyone involved knows it.

What happens in practice is one of four things. A neighbouring authority agrees to take a stated number, recorded in the statement and allocated in its own plan. The authorities agree that the need cannot be met and the plan proceeds with a shortfall, which weakens it. A joint or combined plan is prepared covering the wider area. Or the matter is left unresolved and the examination becomes difficult.

For a developer the second outcome is the interesting one. A plan adopted with an acknowledged shortfall, or an authority without a five-year supply, changes the balance on an application in open countryside, and the statement of common ground is the document that proves the shortfall exists.

Failure of the duty at examination

Failure of the duty to cooperate cannot be remedied during examination. That single procedural fact is why the duty matters more than its wording suggests.

Soundness defects can be fixed. An inspector can recommend main modifications, the authority consults on them, and the plan is adopted in amended form. A duty failure is different: the inspector must recommend that the plan is not adopted, and the authority has to go back and start the engagement properly before resubmitting.

Several authorities have withdrawn plans rather than receive that recommendation, losing years of work and the fees that went with it. For anyone promoting a site through a local plan, the duty is therefore a programme risk worth monitoring, because a failure resets the timetable entirely.

Using the statement in an application

Statements of common ground are public documents and they are useful evidence in a planning application or appeal.

Four ways to use one. To establish that the authority has acknowledged unmet housing need. To show that a strategic matter the officer treats as settled is in fact disputed between authorities. To identify infrastructure commitments another body has made, which can support a scheme's deliverability case. And to date the authority's own position on a question, which matters when policy has moved since.

Cite it precisely in the Planning Statement, with the signatory bodies, the date and the paragraph. Officers take it seriously because their own council signed it. Where a neighbourhood plan also covers the site, check both, since the question of which neighbourhood plan applies can change the policy framework entirely.

What replaces it under reform

The Levelling-up and Regeneration Act 2023 provides for the duty to cooperate to be removed and replaced with an alignment requirement expressed through national policy, alongside wider plan-making changes. The intention is a clearer test of whether authorities have aligned their plans on strategic matters.

As at October 2026, the date the replacement takes effect and its detail should be checked rather than assumed, because the plan-making reforms have arrived through regulations and transitional arrangements over several stages. Follow the changes through the planning law updates timeline and read the current national policy wording before relying on either regime.

One point is worth separating from the reform noise. The removal of a statutory duty does not remove the practical need for authorities to agree figures across a housing market area, because the evidence base still has to add up and an inspector will still ask who else was consulted. Whatever the test is called, the document that answers it will look much like a statement of common ground.

Until the replacement is fully in force, the practical advice is unchanged. Document the engagement, name the figures, record the disagreements, and get the statement signed by someone with authority to sign it. Keep the signed versions, because a statement superseded two years later is still evidence of what the authority thought at the time, and that is often the more useful document.