Documents for a retail unit above the impact threshold
The sequential test has no threshold. The impact assessment has one, set locally or defaulting to 2,500 square metres. Here is what each document has to contain.
Retail impact threshold documents are triggered by a number, and the number is either in your local plan or it is 2,500m². National policy requires an impact assessment for retail and leisure development outside a town centre, not in accordance with an up-to-date development plan, where the gross floorspace exceeds a locally set threshold. Where the plan sets no threshold, the default of 2,500m² applies.
Check the local figure first. Many authorities set thresholds far below the national default, sometimes at a few hundred square metres, specifically to catch schemes on edge of centre sites. A scheme at 1,800m² can be below the national threshold and above the local one.
What the threshold triggers
Two requirements, which are separate and often conflated.
The sequential test applies to main town centre uses proposed outside a town centre and not in accordance with the plan, regardless of floorspace. There is no threshold for it.
The impact assessment is the one the threshold governs. It considers the impact of the proposal on existing, committed and planned investment in centres within the catchment, and the impact on town centre vitality and viability, including local consumer choice and trade in the centre and the wider area, up to ten years from the time the application is made.
So a 400m² out of centre unit needs a sequential test and no impact assessment, while a 4,000m² one needs both. Getting that right at the outset saves commissioning work you do not need.
Sequential test evidence and site search
This is the part that fails most often, and it fails on method rather than on conclusion.
Agree the search area with the officer before the search is done. The area should reflect the catchment the proposal serves, and it should include the centres identified in the development plan's own hierarchy. A search area drawn to exclude the obvious town centre site will be rejected along with everything built on it.
The output is a schedule, not a narrative. For every site identified in the search area, record its address, area, current use, planning status, ownership where known, and the reason it is or is not sequentially preferable. Discount a site only on availability, suitability or viability, and evidence each.
The courts have been clear that suitability is judged against the development proposed rather than against a notional scheme the applicant would not build, but flexibility is still expected. A requirement for 4,000m² on a single floor with 200 surface parking spaces, presented as immovable, invites the response that the requirement has been written to produce the answer.
A Sequential Test (Retail) document that includes the search area plan, the site schedule and the evidence for each discount is far harder to dismiss than one that asserts no sites are available.
Retail impact assessment scope
Scope it with the officer, and ideally with the authority's retail adviser, before any survey work is commissioned.
The elements to settle:
- The study area and its zones, normally drawn from the authority's own retail study where one exists
- The data source for expenditure and market share, and its vintage
- Whether a household telephone or online survey is needed, or whether the existing published study is accepted
- The base year, the design year and the ten year horizon
- Which centres are assessed for impact, and which are health checked
- The treatment of commitments, meaning permitted but unimplemented floorspace
| Element | What it establishes |
|---|---|
| Catchment and zones | Where the trade comes from |
| Expenditure per head and growth | The size of the market |
| Market shares before and after | Trade diversion from each centre |
| Turnover of the proposal | Sales density applied to net sales area |
| Health checks | The resilience of the affected centres |
| Commitments | Cumulative effect with other consents |
The turnover figure is where assessments diverge most. A sales density assumption drives the whole diversion calculation, and it should be sourced and stated rather than assumed. A Retail Impact Assessment that reports a single turnover figure with no source invites a competing figure.
Transport and servicing material
Above 2,500m² of floorspace a full Transport Assessment is normally required rather than a statement, and retail generates the trip patterns highway authorities dislike most: peak Saturday flows, high turnover parking and frequent deliveries.
What to provide beyond the standard assessment: a servicing and delivery analysis showing vehicle types, frequencies and swept paths, a parking accumulation study rather than a flat space count, the pedestrian and cycle routes from the nearest centre and residential areas, and a Saturday peak assessment, because a weekday model will understate the position.
Deliveries matter disproportionately on edge of centre sites where the service yard adjoins housing. Expect a delivery hours condition and a Waste Management Strategy covering the trade waste arrangements.
Design and frontage information
Out of centre retail is the sector most prone to standardised buildings dropped onto a car park, and officers now resist that.
Provide street elevations in context, a plan showing the relationship between the entrance and the pedestrian route, the treatment of any blank elevation facing a highway, boundary treatments, and the parking layout with tree planting shown at mature canopy size rather than as a dot.
Where the site is edge of centre, the connection to the centre is the material point. A 200 metre walk across a car park with no crossing is a reason to doubt the linked trip assumptions in the impact assessment, and an officer will join those two documents together even if you have not.
Economic and employment evidence
An Economic Impact Assessment is worth providing where the scheme claims employment or regeneration benefits, because those claims will otherwise be weighed without evidence.
Keep it honest and consistent with the impact assessment. If the retail assessment says trade is diverted from existing centres, some of the jobs claimed are displaced rather than new, and the economic assessment has to apply that deduction. Two documents claiming the same jobs as additional while the other claims substantial diversion is the inconsistency most often picked up.
Report in full-time equivalents, separate construction from operational employment, and state the source of every density assumption.
Conditions on floorspace and goods ranges
The permission will be conditioned to hold the development to what was assessed, and the wording is worth negotiating.
Expect conditions fixing the gross and net sales floorspace, restricting the installation of a mezzanine, controlling the subdivision of the unit into smaller units, and in many cases restricting the range of goods sold, typically by limiting comparison goods floorspace or specifying the proportion of convenience to comparison.
Three practical points. A goods range condition drafted around a current operator's format causes problems when the operator changes, so argue for a condition expressed in floorspace terms rather than in brand or product terms. A mezzanine restriction is routine and reasonable, since an unrestricted mezzanine can add a third again to the assessed floorspace. And subdivision conditions should state the minimum unit size, because a condition simply prohibiting subdivision can block a letting that has no retail impact at all.
An illustrative scope
A 3,200m² gross food store on an edge of centre site, where the local plan sets a 1,000m² threshold. The pack: a sequential test with an agreed search area plan and a schedule of eleven sites with reasons, an impact assessment using the authority's own retail study zones with a base year, a 2030 design year and a ten year horizon, a transport assessment including a Saturday peak and a parking accumulation study, a servicing analysis with swept paths, an economic assessment applying the diversion-based displacement deduction, design drawings in context, and a trade waste strategy. Seven documents. The figures are illustrative and local thresholds must be checked.
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Frequently asked questions
What is the retail impact threshold?
National policy requires an impact assessment for retail and leisure development outside a town centre, not in accordance with an up-to-date plan, where gross floorspace exceeds a locally set threshold, or 2,500 square metres where the plan sets none. Many authorities set much lower local figures, so always check the adopted plan first.
Does the sequential test have a floorspace threshold?
No. It applies to main town centre uses proposed outside a town centre and not in accordance with the development plan, whatever the size. A small out of centre unit can therefore need a sequential test but no impact assessment, which is why the two requirements should be separated at the outset.
How flexible does a sequential test have to be?
Suitability is judged against the development proposed rather than a notional alternative, but genuine flexibility on format, scale and layout is still expected. A requirement framed so tightly that only the application site can meet it tends to attract the response that the brief was written to produce the desired answer.
What drives the trade diversion figure?
The assumed turnover of the proposal, which comes from a sales density applied to net sales area, combined with market share assumptions before and after. The sales density should be sourced and stated rather than assumed, because an unsourced figure invites a competing one and the whole diversion calculation rests on it.
Can a condition restrict what goods are sold?
Yes, and it is common on out of centre retail. The useful negotiation is over the drafting: a condition expressed in floorspace terms, such as a cap on comparison goods floorspace, survives a change of operator, while one written around a particular retailer's format causes problems later. Mezzanine and subdivision restrictions are also routine.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.