Splitting a site to stay below a planning threshold

Splitting a site to stay below a planning threshold works far less often than it used to, and it fails in ways that cost more than the obligation it was meant to avoid. Two applications for nine dwellings each, on land in the same ownership, sharing an access and submitted a fortnight apart, will be treated as one scheme of eighteen by any officer who has been in the job a year.

The temptation is understandable. Ten dwellings is where affordable housing arrives, where major development procedures start, and where the evidence base steps up.

Why applicants split sites

The thresholds that drive it are easy to list. Major development in England means ten or more dwellings, a site of 0.5 hectares or more where the number is not known, or 1,000 m2 of floorspace or one hectare for other development. Affordable housing is generally not sought below major development, other than in designated rural areas where a plan may set a lower threshold. Statements of community involvement, transport assessments, environmental statements and committee referral all have their own trigger points.

Below those lines the application is quicker, the fee is lower, the consultation is narrower and the section 106 negotiation may not happen at all. The arithmetic looks attractive on a spreadsheet.

It looks different once you add the cost of a refusal, a screening direction and twelve months of delay.

How authorities identify a split

Officers are not guessing. The indicators are mostly on the file already.

• Red lines that adjoin, or that are separated by a strip of land in the same ownership.
• The same applicant, the same agent, the same architect and consecutive reference numbers.
• Blue line land shown on the certificate that covers the neighbouring parcel.
• A single access serving both parcels, or an access on one parcel that only makes sense if the other is developed.
• Drainage or open space that only works across the whole area.
• Site history showing an earlier application for the combined area.

Ownership certificates are the quiet trap. Certificate A signed for parcel one, when the applicant also owns parcel two, and certificate A signed again for parcel two a fortnight later, tells the authority everything it needs to know.

Cumulative assessment in screening and policy

For environmental impact assessment the point is settled. Screening under the Town and Country Planning (Environmental Impact Assessment) Regulations 2017 must consider the project as a whole, and the selection criteria in Schedule 3 expressly include cumulation with other existing or approved development. The courts have held that functionally interdependent applications should be screened together rather than separately, and where an authority screens out a split scheme the Secretary of State can issue a screening direction.

The consequence is not a polite request. An Environmental Impact Assessment required after permission has been granted puts the permission at risk, and a decision taken without considering environmental information that should have been before the authority can be quashed.

Policy thresholds are less codified but work the same way. Local plans increasingly define residential development by reference to the site rather than the application, and where they do not, officers rely on the general principle that a planning judgement is made on the substance of what is proposed. An Affordable Housing Statement that addresses nine units on a site plainly capable of eighteen invites the question rather than answering it.

Highways is the third area. Trip generation is assessed on what the road network will actually receive, so a Transport Assessment scoped to half a scheme gets rejected by the highway authority rather than the planning officer.

Where phasing is legitimate

None of this makes phasing improper. Phasing is normal, and there are good reasons to bring land forward in parcels.

Real separation usually shows up as several of the following together: different landowners with no common interest, separate accesses onto different roads, parcels that can be built and occupied independently, different delivery timescales driven by tenure or funding, and an application that would stand on its own if the neighbouring land never came forward.

The cleanest route where the whole area is yours is an outline application for the full site with a phasing plan, followed by reserved matters by phase. It fixes the obligations across the whole scheme, allows the levy to be paid by phase, and removes the argument entirely. Where the scheme is small enough that outline is disproportionate, a full application for the whole site with a phased start condition does the same job.

Splitting an application to manage cash flow is legitimate. Splitting it to change which policies apply is not, and the difference is usually visible in the drawings.

Consequences when a split is rejected

The mildest outcome is a request to withdraw and resubmit as a single application. That costs a fee and two months.

Worse outcomes follow from permission being granted and the split being identified later. Obligations can be sought on the combined scheme through a subsequent application, and authorities have long memories when a second parcel comes forward. Enforcement is available where the development carried out differs from what was permitted. And a third party with the resources to bring a claim can challenge a permission granted without proper screening.

There is also a reputational cost that practitioners underrate. An agent who has run a split once will find the next application from the same client read with more care, and pre-application discussions become less useful when the officer assumes the red line is not the whole story.

Where the question is really about what changes between one dwelling and two on the same plot, that is a different issue with its own answers, covered in our note on two dwellings on one plot.

Obligations triggered on the combined scheme

If an authority concludes the parcels form one development, the obligations follow the combined figures. Affordable housing is calculated on the total. Education and open space contributions are calculated on the total child yield and the total population. Where the combined scheme crosses 150 units, a national consultee on active travel comes into play.

Retrospective negotiation is worse than negotiating up front, because the applicant has lost the option of designing the scheme around the obligation. A tenure mix agreed at the start can be delivered efficiently. The same percentage imposed on a scheme already designed as open market housing usually means redrawing.

Committee referral thresholds move too, and the delegation scheme for a nine unit scheme is rarely the same as for eighteen. We have set out how those work in our note on committee referral thresholds and delegated decisions.

Setting the red line honestly

The red line should include the application site and everything needed to implement the permission, including access. Other land in the applicant's control goes inside the blue line. Getting that right is not a courtesy to the authority; an incorrect certificate can invalidate the application and, in some circumstances, the permission.

Practical discipline for anyone assembling a submission:

1. Draw the red line around what will actually be built and accessed.
2. Show all land in the applicant's ownership or control in blue, including options and conditional contracts.
3. Serve notice on any other owner under the correct certificate, and keep the proof.
4. Say in the covering letter how the application relates to any adjoining land in the same ownership, and what the intentions for it are.
5. If a phased approach is intended, propose the phasing yourself rather than waiting to be asked.

That last step converts a suspicion into a negotiation. Officers respond well to an applicant who sets out the whole picture and explains the programme, and badly to one who is found out.

Browse the 66 report types to see which evidence a scheme needs once it crosses into major development.

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