Splitting a site to stay under a threshold, and why it fails

Subdividing a scheme so that each application falls below the major development threshold does not work, and it usually costs more than it saves. A local planning authority is entitled to look at what is actually being built, and where two or more applications form part of a single scheme it will assess them together, screen the whole project for environmental impact, and apply the affordable housing and infrastructure requirements that the combined figure triggers. The tactic is well known, it has a name in every planning department, and the officers who spot it become less helpful about everything else.

Major development means ten or more dwellings, or a site of 0.5 hectares or more where the number is not yet known, with equivalent floorspace and area tests for other uses. That line is what applicants try to stay under.

Why applicants try to stay below the line

Crossing the threshold changes the application in several directions at once, and each change carries cost.

Determination moves from eight weeks to thirteen. Affordable housing requirements engage, so a nine unit scheme in a district with a ten unit threshold pays nothing and a ten unit scheme pays. More statutory consultees appear, and the documents they expect appear with them. Publicity requirements increase. A Statement of Community Involvement becomes a validation item in many authorities, and an Affordable Housing Statement becomes unavoidable.

The arithmetic looks compelling on a spreadsheet. Two applications of five and five, made three months apart under two company names, appear to remove the affordable housing contribution entirely.

How authorities test related applications

Case officers ask a short series of questions, and they ask them of the land rather than of the paperwork.

Is the land in common ownership, or was it in common ownership when the applications were made. Does one application rely on an access, a drainage connection or an open space that lies within the other. Were the applications submitted by the same agent, the same applicant or related companies. Do the site plans abut. Is there a physical or functional reason why the parcels would be developed independently. Does the wider site have a single allocation, a single boundary in the local plan or a single pre-application reference.

None of those is conclusive on its own. Together they establish whether there is one scheme, and the officer report will say so in terms.

Authorities also have the benefit of hindsight. Applications are public, they are recorded against the address, and a second application on the adjoining parcel will be matched to the first by a search of the address history. Where a scheme is built out as one site, with one access and one site office, the enforcement team can see it.

Cumulative effects and the screening duty

Environmental impact assessment is where the practice becomes legally dangerous rather than merely unwise.

The Town and Country Planning (Environmental Impact Assessment) Regulations 2017 require screening of the project. The courts have consistently held that a project cannot be divided artificially so that its parts each fall below a threshold, and an authority that screens only the parcel in front of it may find its decision challenged. Screening has to consider the development as a whole, including cumulation with other existing and approved development.

The same logic runs through the rest of the evidence base. Transport assessment thresholds respond to the total trip generation, not to the parcel. A Transport Assessment prepared for five dwellings when 20 are being built describes a network condition that does not exist. Flood risk and drainage are assessed catchment wide, so a drainage strategy for part of a site produces a run-off rate that the whole site will exceed.

Where an Environmental Impact Assessment is required, the Environmental Statement must be prepared by competent experts under the 2017 Regulations, and an AI-assisted draft is a starting point for that team rather than a substitute for it.

Single planning unit and common ownership

The planning unit concept underlies the whole question. Where the land forms one unit in single ownership and occupation, the development being carried out on it is one development, whatever the application forms say.

Transferring parcels into separate companies before applying is a familiar attempt to break the link, and it rarely persuades. Authorities look at the beneficial ownership, the option agreements, the sequence of transfers and the dates. A transfer made a fortnight before the second application, to a company with the same registered office as the first applicant, tells its own story.

Genuine separation does happen. Two neighbouring owners each developing their own garden, with separate accesses, separate drainage and no coordination, are making two applications and should be assessed as two. The distinction is real and authorities recognise it when the facts support it.

Consequences when the tactic is spotted

The outcomes are worse than paying the contribution would have been.

• The second application is assessed as part of a major scheme, with the full requirement applied and no credit for what the first application avoided.
• An obligation may be sought on the second application covering the whole scheme, which loads the entire contribution onto one parcel.
• A screening opinion may be issued for the combined project, adding months.
• Where permission has already been granted on a misleading basis, the authority may consider whether it was obtained by misrepresentation.
• At appeal, an inspector who concludes the applications form one scheme will assess it as such, and costs applications follow unreasonable behaviour.
• The relationship with the authority deteriorates, which matters on every condition discharge for the next two years.

Where phasing is legitimate instead

Phasing a large scheme is normal, expected, and entirely lawful. The difference is that phasing is declared.

The established routes are an outline permission with phases defined by condition, a full permission with a phasing plan approved under condition, or a section 106 agreement that sets obligations by phase with triggers tied to unit numbers within each. Each of those tells the authority the full extent of the scheme and then spreads delivery over time, which is the legitimate version of the cash flow benefit that subdivision was chasing.

The practical advantages are real. Obligations fall due phase by phase rather than at the start. Infrastructure can be sized for the whole and built in stages. Reserved matters can respond to market conditions. And the evidence base is prepared once for the whole site, which costs less than preparing it twice for two halves. The consultees that arrive as a scheme grows are dealt with in one conversation.

Presenting a phased scheme honestly

1. Define the whole site in the red line, even where only part is to be built first.
2. State the total number of units and the total site area on the application form.
3. Submit a phasing plan showing the sequence and the extent of each phase.
4. Prepare the transport, drainage and ecology evidence for the whole site, with phase specific detail where needed.
5. Set out the affordable housing position for the whole scheme, and how it is delivered by phase.
6. Propose obligation triggers by phase, tied to unit numbers rather than to dates.
7. Where a later phase is uncertain, say so and explain what happens if it does not proceed.

An illustrative example: a 1.2 hectare paddock capable of 18 dwellings. The first plan is two applications of nine, three months apart, through two companies. The officer identifies a shared access shown on both site plans and treats them as one scheme, issues a screening opinion for 18 units and applies the affordable housing requirement in full to the second application. The applicant withdraws and resubmits a single outline application for 18 dwellings in two phases, with the contribution split by phase and triggered on the tenth and fifteenth occupations. The scheme is approved with a cash flow close to what the original plan was trying to achieve, and without the eight months lost.

Housing mix and space standards also change as a scheme crosses these lines, and how the requirements grow with scale is worth mapping before you fix the unit count.

PlanScope drafts the supporting documents a phased scheme needs, from your site details and answers, structured to UK planning policy and flagging the facts it cannot verify. This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.