Flood sequential test or retail sequential test
One asks whether the development could sit on land at lower flood risk. The other asks whether it could sit in a town centre. They can point in opposite directions on the same site.
Two completely unrelated planning tests share the word sequential, and a scheme can need both. The flood sequential test asks whether the development could go somewhere at lower risk of flooding. The retail sequential test, properly the sequential approach for main town centre uses, asks whether it could go in a town centre instead of out of one. Searching for flood sequential test or retail sequential test guidance turns up both, and applying the wrong one wastes a consultation period.
They differ in what they ask, who defines the area of search, what counts as a reasonable alternative, and what gets you out of them.
What each test asks
The flood test is a steer towards lower risk land. National flood risk policy and the Planning Practice Guidance on flood risk and coastal change require development to be directed to areas with the lowest risk of flooding from all sources. If the development can reasonably be located on a site at lower risk, it should be. Fail the test and the application should be refused, regardless of how good the mitigation is.
The retail test is a steer towards centres. National town centre policy requires main town centre uses to be located in existing centres first, then on edge of centre sites, and only then out of centre, with applicants demonstrating flexibility on format, scale, car parking provision and the scope for disaggregation.
The underlying purpose differs too. The flood test manages risk to people and property. The town centre approach supports the vitality of centres. That distinction matters when you write the statement, because the reasoning that persuades on one will not persuade on the other.
Area of search in flood and retail terms
The flood area of search is normally agreed with the local planning authority and is often the authority's administrative area, though it can be wider or narrower depending on the nature of the development. A site specific operational need, such as a replacement building for an existing business, can justify a tight area. A speculative housing scheme cannot.
The retail area of search follows the catchment the proposal would serve and the centres within it, as identified in the development plan's hierarchy. It therefore crosses administrative boundaries more readily, and neighbouring authorities may be consulted where their centres would be affected.
The two searches can produce opposite answers. A town centre is frequently the lowest lying part of a settlement, built around a river, so the sequentially preferable retail site may be the sequentially worst flood site. Where that tension arises, agree the approach with the authority in writing at pre-application stage rather than picking one and hoping.
Availability, suitability and viability
Both tests turn on whether an alternative site is really an alternative, and both use similar vocabulary with different emphasis.
For flood, the question is whether a site at lower risk is reasonably available for the development proposed. Availability means available to the market within a reasonable period, not available in principle.
For retail, the Supreme Court addressed suitability in Tesco Stores Ltd v Dundee City Council [2012], holding that suitability is assessed by reference to the development proposed rather than to some notional alternative scheme the applicant has not put forward. That has been the anchor point for the argument ever since, alongside the requirement for genuine flexibility.
Viability sits awkwardly in both. A site that cannot be delivered at any realistic cost is not a reasonable alternative, but an applicant's preference for a more profitable site is not a reason to discount a sequentially preferable one. Evidence a viability argument properly or leave it out.
Who decides the scope
The local planning authority decides the scope of both, and in each case a consultee has a strong voice.
For flood risk, the Environment Agency comments on development in Flood Zones 2 and 3 and on sites of a hectare or more, and the lead local flood authority on surface water drainage for major development. For town centre proposals, the authority's own retail evidence base and sometimes a neighbouring authority shape the assessment.
Settle the scope first. A sequential test statement written against an area of search the authority does not accept is worth nothing, however careful the site schedule.
Evidence each test needs
Both tests are evidenced with a site schedule and a reasoned rejection of each alternative. The content differs.
| Flood sequential test | Retail sequential approach | |
|---|---|---|
| Question | Is a site at lower flood risk reasonably available | Is a site in or edge of centre available and suitable |
| Area of search | Normally agreed with the authority, often the LPA area | The catchment and the centres serving it |
| Source of sites | Allocations, availability assessments, market search | Centre boundaries, allocations, market search |
| Discount reasons | Flood zone, size, availability, operational need | Availability, suitability for the proposal, size, access |
| Key authority | Environment Agency comments on the flood position | The authority's retail evidence base |
| Failure consequence | Refusal, before any mitigation is considered | Refusal, or assessment moves to impact |
For flood, the schedule should give each candidate site's flood zone taken from the current official mapping, its size, its planning status and the reason it is discounted. Where the test is passed and risk remains, the Exception Test follows, with its two limbs on wider sustainability benefits and on the development being safe for its lifetime without increasing flood risk elsewhere.
For retail, the schedule should show the search area, the centres considered, the sites within and adjoining them, and the flexibility applied to format and scale. Where the proposal exceeds the applicable impact threshold, an impact assessment follows, and the national floorspace threshold applies unless the development plan sets a local one.
Exceptions and exemptions
This is where most time is saved.
The flood test does not need to be applied where a site is allocated in a development plan and the test was applied at plan making stage, provided the proposal accords with the allocation. The Planning Practice Guidance also disapplies it for minor development and for changes of use, with stated exceptions such as changes of use to a caravan or camping site. Householder extensions are outside it.
The retail approach does not apply to proposals in an existing centre, nor to proposals in accordance with an up-to-date development plan, nor to uses that are not main town centre uses. Classifying the use correctly is therefore the first task, and it is the step most often skipped.
Check both exemptions before commissioning anything. A sequential test statement for a development that was exempt is a fee nobody needed.
Running both on one site
Where an out of centre retail or leisure proposal sits in Flood Zone 2 or 3, both apply, and the order to work in is to establish the use classification, then the retail area of search, then the flood area of search informed by it.
Write them as two separate statements rather than one hybrid document. Different consultees read them, they cite different policy, and a combined document tends to satisfy neither. Cross-refer between them where the site schedules overlap.
Where an existing permission is amended and the scheme changes materially in use or floorspace, the tests may need revisiting, and the mechanics of the amendment route are set out in the note on section 73 against section 96A. Where the application is refused, the appeal route and timescale depend on the application type, as described in the note on householder and fast track commercial appeals.
Browse the full index of report types to see where each sequential test and the flood exception test sit in a submission, then start a draft on PlanScope.
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.
Frequently asked questions
Are the flood and retail sequential tests related?
No, beyond the shared word. The flood test directs development to land at lowest risk of flooding from all sources. The town centre sequential approach directs main town centre uses to centres first, then edge of centre, then out of centre. They cite different policy, serve different purposes and are read by different consultees.
Who decides the area of search?
The local planning authority in both cases. For flood the area is normally agreed with the authority and is often its administrative area, narrower where there is a site specific operational need. For retail it follows the catchment the proposal would serve and the centres within it, which can cross administrative boundaries.
What did the Dundee case decide?
In Tesco Stores Ltd v Dundee City Council [2012] the Supreme Court held that suitability in the retail sequential approach is assessed by reference to the development proposed rather than some notional alternative scheme the applicant has not put forward. It remains the anchor point for the argument, alongside the requirement to show real flexibility.
When is the flood sequential test not needed?
Where a site is allocated in a development plan and the test was applied at plan making stage, provided the proposal accords with the allocation. The Planning Practice Guidance also disapplies it for minor development and for changes of use, with stated exceptions such as changes to caravan or camping sites. Householder extensions sit outside it.
What if a site needs both tests?
Establish the use classification first, then the retail area of search, then the flood area of search informed by it. Write two separate statements rather than a hybrid document, because different consultees read them and they cite different policy. Cross-refer where the site schedules overlap.
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.