Sequential and Exception Test Reports for Planning Permission

The Sequential Test is the planning-policy mechanism that steers new development towards land at the lowest risk of flooding, and it is one of the most common reasons flood-risk sites stall in the planning system. If your proposal sits in Flood Zone 2 or 3, or is flagged for surface water risk, the local planning authority can decline to grant permission until Sequential Test evidence (and, in higher-risk cases, Exception Test evidence) is in front of the case officer.

Unda prepares Sequential Test and Exception Test reports for planning applications, site allocations and appeals across England. Our consultants have produced more than 5,000 flood risk assessments since 2014, and we build sequential and exception testing into a wider flood risk strategy rather than treating it as standalone form-filling. That matters more than usual at the moment: on 17 August 2026 the government published a new National Planning Policy Framework that rewrites how both tests work, and it applies to decisions from the day it landed.

Needing a Sequential Test does not mean your site is undevelopable. It means the authority needs evidence that no reasonably available lower-risk site could accommodate your development. That evidence can be assembled, and argued, properly.

What is the Sequential Test?

The Sequential Test is a national planning policy requirement in England that directs new development to the areas with the lowest probability of flooding. Where development is proposed in an area at flood risk, the applicant has to demonstrate that there are no reasonably available sites at lower risk that could accommodate it. If such a site exists, the proposal should go there instead.

In the August 2026 National Planning Policy Framework the test sits in Policy F5, within a dedicated flood-risk chapter running from Policy F1 to F9. That is a move from the December 2024 Framework, where it lived at paragraphs 173 to 175 and leaned heavily on separate planning practice guidance. The objective is unchanged: steer development to Flood Zone 1 first, then Zone 2, and only then Zone 3, taking account of flood risk from every source and of how climate change will shift that risk over the development's lifetime. We set the wider Framework out in our guide to planning for flood risk under the NPPF and in our NPPF guidance hub.

The Sequential Test applies in England. Wales runs a different regime under TAN15, where flood risk evidence takes the form of a Flood Consequence Assessment rather than sequential testing against England's flood zones.

When is a Sequential Test required?

A Sequential Test is normally required where development is proposed in an area at flood risk from any source and no exemption applies. In practice the common triggers are these.

• Flood Zone 2 or 3. The site sits in one of these zones on the Flood Map for Planning, including land in the functional floodplain (Zone 3b).
• A climate-change extent. The site falls within a "Flood Zones plus climate change" layer, the mapped area showing where Zones 2 and 3 are expected to spread as the climate changes.
• Surface water risk. The site is affected by surface water flooding, including sites that are in Flood Zone 1 for rivers and the sea. Our guide to the Flood Map for Planning explains the surface water layers, which since the May 2026 update carry climate-change extents and banded depth data.
• A local requirement. The planning authority or its Local Plan asks for the test, through a validation request or a development-plan policy. Our note on how local planning authorities handle flood risk covers where it fits in the process.
• An FRA finding. A Flood Risk Assessment identifies a constraint that pulls the site into sequential testing even where the mapping alone did not.

There are exemptions. Householder development, small non-domestic extensions below 250 square metres and most changes of use fall outside the test, as do sites allocated in an up-to-date Local Plan where the test was properly applied at allocation. And where the only flood risk is surface water, Policy F5(2)(b)(ii) now removes the test entirely if a site-specific FRA clearly demonstrates that occupants will be safe for the development's lifetime without increasing flood risk elsewhere. The gates below show how those routes interact.

Getting this screening step right at the outset saves months. A proposal submitted without the Sequential Test evidence it needs is a straightforward validation or refusal point for the authority. Since the April 2026 appeal reforms narrowed the scope for introducing new evidence at appeal, flood risk evidence increasingly has to be right first time.

What changed in the August 2026 NPPF

The refresh matters because it moves several long-argued questions out of guidance and case law and into national policy. Our full analysis of the August 2026 NPPF flood and drainage changes covers the detail; for the two tests, these are the changes that bite.

• A dedicated flood chapter. Flood risk and coastal change now have their own chapter, Policies F1 to F9, with the flood zone definitions, the vulnerability classification and the compatibility matrix consolidated into Annex F rather than scattered across footnotes and guidance.
• The Sequential Test becomes Policy F5. The area of search is now capped in policy: it should not be greater than the anticipated catchment of the development in terms of its likely occupiers or users. That is a harder-edged limit than the old proportionality wording, and one that applicants for local development can cite directly against borough-wide search demands.
• The surface-water exemption is hardened into national policy. What began as a narrow carve-out in the September 2025 guidance is now Policy F5(2)(b)(ii). The site-specific FRA becomes the document that carries it, so the surface water assessment stops being a supporting chapter and becomes the evidence the case turns on.
• The Exception Test becomes Policy F6, with three limbs. The old two-part test gains a free-standing third limb: the development must not increase flood risk elsewhere and, where possible, should reduce it overall. It is now confined expressly to river and sea flooding in Flood Zones 2, 3a and 3b.
• Refusal wording replaces permissive wording. Policies F6 and F7 are drafted as "should be refused unless", and incompatible uses under Annex F Table 3 now carry an explicit refusal instruction, wired into the Framework's decision-making architecture rather than left to open-textured "should" language.
• It applies now, including to live applications. The new policies are material to every application determined from 17 August 2026, including those submitted under the old Framework, and local plan policies that conflict with them carry very limited weight. From 31 October 2026 a national scheme of delegation moves most decisions to officers, so an unresolved Environment Agency or lead local flood authority objection weighs even more heavily.

None of this makes the underlying skill any less important. If anything, the higher evidential bar rewards a report built for scrutiny. The tests that had been settled by the Mead, Gladman and Yatton line of decisions now have a policy answer, and the first appeals testing how much of that case law survives the new wording will be closely watched.

Sequential Test vs Exception Test: what is the difference?

The two tests are sequential in more than name. The Exception Test only ever arises after the Sequential Test, and only for certain combinations of flood zone and development vulnerability. The comparison below is the short version.

How to pass the Sequential Test

A Sequential Test succeeds or fails on three judgements: how the area of search is drawn, which alternative sites are treated as reasonably available, and how honestly the comparison is evidenced. The authority makes the final call, so the report has to anticipate scrutiny.

Defining the area of search

The search area must be proportionate to the scale and nature of what you are proposing and the needs it serves. Policy F5(1) now caps it at the anticipated catchment of the development: for a village shop, a GP surgery or an estate regeneration, that is a local catchment, not the whole district. Infrastructure of regional importance can justify a wider search. Where large parts of a settlement sit in flood risk areas, the test has to be applied pragmatically, and the local Strategic Flood Risk Assessment is usually the starting evidence base.

Identifying reasonably available sites

Sites count as reasonably available where they are suitable for the development proposed, can meet the same need, and have a reasonable prospect of coming forward in a similar timeframe. They need not be in your ownership, and several smaller sites can be combined into an alternative. Equally, the courts have confirmed you cannot define the proposal so narrowly that only your own site could ever satisfy it.

Evidencing the comparison

The report then compares each candidate site against your own on flood risk from all sources, suitability, availability and capacity, and sets out the planning-policy justification for the conclusion. Weak Sequential Tests tend to fail on the same points: search areas drawn to exclude awkward competitors, alternative sites dismissed without evidence, and no engagement with the SFRA or the council's own land-availability assessments.

When is the Exception Test required?

The Exception Test applies where the Sequential Test has shown there is no reasonably available lower-risk site, but national policy still requires further justification because of what is being built and where. Under the August 2026 Framework the trigger is set by Annex F Table 3, which reads the development's flood risk vulnerability classification against the flood zone, and for the first time it states an explicit "should be refused" outcome for incompatible combinations. The matrix below shows where the test bites for river and sea flooding.

To pass, all three limbs must now be satisfied. First, the development must deliver wider sustainability benefits to the community that outweigh the flood risk: affordable housing, regeneration and infrastructure commonly feature. Second, it must be safe for its lifetime, taking account of the vulnerability of its users and, expressly now, its visitors. Third, it must not increase flood risk elsewhere and, where possible, should reduce it overall. For housing, "lifetime" is normally taken as at least 100 years, which is why the Environment Agency's climate change allowances run right through Exception Test evidence: flood levels, finished floor levels and safe access all have to work under future conditions, not today's alone.

An Exception Test report is therefore inseparable from the site-specific Flood Risk Assessment, and on more complex sites from the hydraulic flood modelling that quantifies depths, hazard and the effect of mitigation. Unda prepares all three as one coordinated evidence package. The vulnerability categories themselves are set out in Annex F Table 2, recently widened so that data centres, electric-vehicle charging and other essential infrastructure have a route through the test. We unpack them in our vulnerability classification guide.

What if the Sequential Test is failed, or missed entirely?

A run of recent decisions has clarified what happens when sequential testing goes wrong, and it cuts both ways. Failing the test is a serious policy conflict, but the courts have confirmed it is not automatically the end of the application: the consequences fall to be weighed in the planning balance alongside everything else. What the August 2026 Framework changes is the weight on the policy side of that balance, because an inspector minded to allow a failed-test scheme must now do so against explicit refusal wording rather than open-textured "should" language.

• Mead (Court of Appeal). Confirmed that the guidance interpretation of the test is lawful and that failure is a matter of weight, not an automatic bar. It is the foundation for everything that followed. See our post-Mead guide.
• Yatton (High Court, June 2026). Outline permission for 190 homes on a Flood Zone 3a site was upheld even though the Sequential Test was failed, with the substance of the Exception Test weighed as material considerations. We cover both the appeal decision and the High Court judgment.
• Faversham (appeal, 2025). 250 homes were allowed despite no Sequential Test having been undertaken, where land raising and drainage design demonstrated the scheme was safe. See our Faversham review.
• Gladman (High Court, January 2026). The counter-case: a refusal was quashed because the inspector treated the absence of a Sequential Test as automatically fatal without carrying out a lawful planning balance. See what the Gladman judgment means.

None of this makes the Sequential Test optional, and the TCPA has argued that a run of permissive decisions risks eroding the safeguard. What it does mean is that how the evidence is framed, and how a shortfall is argued in the balance, can decide the outcome. That is where an experienced consultant earns their fee, particularly at appeal.

Is this the right flood risk service for you?

Sequential and Exception Test reports are one part of Unda's flood risk work, and searches often land people here who need something adjacent. A quick router.

• Applying for planning permission on a flood-risk site? You will usually need a site-specific Flood Risk Assessment for planning first. Sequential testing is often commissioned alongside it.
• Developing in Wales? You need a Flood Consequence Assessment under TAN15, not an English Sequential Test.
• Buying a home or property flagged for flood risk? Our flood risk survey for property purchase is the service you want.
• Struggling with flood insurance? A flood risk assessment for insurance gives underwriters property-level evidence.
• Chasing BREEAM credits? See our BREEAM flood risk assessments for Pol 03.
• Handling surface water or drainage conditions? Our SuDS and drainage strategy team handles those, now that Policy F8 makes the national SuDS standards mandatory.

Not sure which applies? Contact us and we will point you at the right service, including telling you if you do not need a Sequential Test at all. Every term on this page is defined in our flood risk and drainage glossary.

What our Sequential and Exception Test reports include

Every report is built to be determination-ready: structured around the current Framework, referenced to the policies the case officer will check against, and written so the authority can adopt its reasoning directly.

• A defensible area of search, defined and justified against the Policy F5(1) catchment cap for your development type and settlement.
• An alternative sites assessment, drawing on the SFRA, the council's land-availability evidence, allocations and call-for-sites data to identify every candidate a case officer might raise.
• A flood risk comparison of each alternative, from all sources, so the comparison is like-for-like rather than zone-label-deep.
• Suitability, availability and capacity analysis, including combinations of smaller sites, with evidence for each conclusion.
• The planning-policy justification, setting out why your site is the most appropriate available location in flood risk terms.
• Exception Test evidence where needed, covering all three limbs and integrated with the Flood Risk Assessment and any flood modelling.

How much does a Sequential Test report cost?

It depends on the shape of the job, and we would rather quote your site than publish a misleading flat rate. The main cost drivers are the scale of the proposed development and the size of the area of search it justifies; how many candidate alternative sites need assessing; whether flood risk on those alternatives can be screened from existing data or needs closer analysis; and whether the Exception Test, with the FRA and modelling evidence behind it, is in scope as well.

A single-settlement search for a small residential scheme is a very different exercise from a strategic land promotion covering a whole district. We explain why bespoke scoping beats a fixed rate in our guide to what drives a flood risk assessment's cost. Tell us what you are proposing and we will price it properly.

Why developers and planning consultants choose Unda

• Policy currency. The Sequential Test has changed more since 2024 than in the previous decade. We wrote the analyses of the September 2025 PPG update, Mead, Gladman, Yatton and the new Framework that other professionals read, and we build that thinking into every report.
• Independence. We are flood risk consultants, not land agents. Our conclusions are evidenced, which is what makes them survive scrutiny by the authority and the Environment Agency.
• One coordinated package. Sequential Test, Exception Test, FRA, modelling and drainage from one team, so the evidence tells a single consistent story.
• England-wide local knowledge. We work area by area, river by river and authority by authority, so we know how individual councils apply the test in practice.
• Appeal experience. Where the test is contested, our reports and our consultants support planning appeals, which matters more now that appeal rules limit new evidence after the original decision.

Want a first look at your site before you commit? Our free flood risk map postcode checker shows the flood zones and surface water picture, and our live river levels map shows what nearby watercourses are doing right now.

How it works

1. Send us the site. An address or a red-line plan, plus what you are proposing. We will confirm whether a Sequential Test is actually required. Sometimes it is not.
2. Fixed quote within 60 minutes. On a working day, one of our flood risk consultants comes back with a tailored, no-obligation quote.
3. We build the evidence. Area of search, alternative sites assessment, flood risk comparison and policy justification, plus Exception Test, FRA and modelling where in scope.
4. You review the draft. We refine the report with your planning consultant or architect so it slots into the wider application narrative.
5. Determination support. If the case officer, the Environment Agency or an appeal raises questions, we respond, because the report is the start of the service, not the end.

Sequential and Exception Test FAQs

Speak to our flood risk consultants

If your development needs a Sequential Test report or Exception Test report, or you suspect it might and want a straight answer either way, our experienced flood risk consultants can advise on the right approach and prepare evidence the planning authority can rely on.

If you need a quote or want to discuss your requirements in more detail, contact one of our experienced flood risk consultants. Call +44 (0) 1293 214444 or email enquiries@unda.co.uk.