The Upper Tribunal rules that expert evidence in the First-tier Tax Tribunal must be tightly controlled in HMRC v Healthspan Limited [2026] UKUT 00194 (TCC). Permission depends on whether it is reasonably required to resolve the proceedings, not simply being helpful. Broadly scoped expert applications risk failing on relevance and proportionality.
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The Upper Tribunal’s decision in HMRC v Healthspan Limited [2026] UKUT 00194 (TCC) provides important guidance on the admission of expert evidence in tax appeals, and the approach the First-tier Tribunal (FTT) should take when deciding whether permission should be granted.
The decision reinforces a central point: expert evidence is not to be admitted merely because it might assist or because a party wishes to deploy it. The correct question is whether, if expert evidence is not necessary to resolve the proceedings, it is nevertheless reasonably required to do so, assessed by reference to the pleaded issues and the overriding objective.
The correct test: “reasonably required”, not merely helpful
The FTT had granted permission for expert evidence on the basis that it might assist the Tribunal and was necessary for the taxpayer to advance its case.
The Upper Tribunal held that this approach was wrong in principle. It confirmed that:
- while the Civil Procedure Rules do not apply directly in the FTT, CPR Part 35 provides the appropriate analytical framework; and
- the starting point is that expert evidence should be restricted to that which is reasonably required to resolve the proceedings.
Critically, the Upper Tribunal rejected the idea that an “assistance” test is sufficient. Evidence may be helpful or informative, but still not proportionate or necessary in the context of the proceedings as a whole.
It endorsed the structured approach derived from British Airways v Spencer [2015] EWHC 2477 (Ch):
- Is expert evidence necessary to resolve a pleaded issue?
- If not, would it assist the Tribunal?
- If it would assist but is not necessary, is it nevertheless reasonably required, taking into account the overall proceedings, proportionality, cost and burden?
This third stage introduces a necessary discipline; even relevant and potentially helpful evidence may properly be excluded where it is not justified by the issues in dispute.
Focus on the pleaded issues
A central criticism of the taxpayer’s application, and of the FTT’s approach, was its failure to tie the proposed expert evidence with precision to the issues in dispute.
The Upper Tribunal emphasised that:
- the Tribunal must identify the pleaded issues with precision;
- it must define what specific questions the expert is being asked to address; and
- a broad or thematic description of evidence will rarely suffice.
A general desire for expert material or an expansive description of topics will not meet the test. The Tribunal must be able to see how the proposed evidence bears on a live issue and what it adds.
This is fundamental to:
- maintaining proportionality;
- avoiding unnecessary cost and complexity; and
- preventing expert evidence from drifting into advocacy or irrelevance.
Rejection of the “kitchen sink” approach
On the facts, the taxpayer sought permission for expert evidence across three broad areas:
- the scientific understanding of food;
- the nutritional profile of the products; and
- the role of the products within the modern diet.
The Upper Tribunal confined permission to a narrow subset of that material, allowing evidence only on the nutritional profile of the products, and rejecting the other strands.
In doing so, it highlighted a number of issues which will resonate in practice:
- overly broad categories of evidence risk generating unfocused and disproportionate material;
- evidence which strays into conceptual or definitional territory risks usurping the Tribunal’s role;
- evidence not clearly anchored in pleaded issues risks becoming a distraction rather than assistance; and
- permission-stage control cannot be deferred — the Tribunal must define the scope at the outset.
The Tribunal expressly warned against opening the door to material which would distract from the task of statutory interpretation and application.
Cost, burden and proportionality
The decision also contains an important reminder that expert evidence imposes immediate cost and burden, not just on the party adducing it but on the opposing party.
The FTT had treated prejudice as minimal on the basis that:
- the opposing party could respond to the evidence later; and
- any unsuccessful reliance would fall in costs.
The Upper Tribunal rejected that approach, noting that granting permission triggers:
- the cost of reviewing and analysing expert material;
- tactical decisions as to whether to respond in kind; and
- potential escalation of the case into expert-driven litigation.
These factors are integral to the “reasonably required” analysis and must be addressed at the permission stage.
Practical implications
The decision provides clear guidance for practitioners:
- Precision is essential
Applications must be tightly framed by reference to pleaded issues. - CPR 35 is the benchmark
Even in tribunal proceedings, the structured CPR approach provides discipline. - Relevance is not enough
Evidence must be necessary, or demonstrably required, not merely helpful. - Scope must be controlled early
The Tribunal will not permit open-ended expert evidence. - Proportionality is central
Cost, burden and impact are integral to the permission decision.
Comment
This decision is a clear endorsement of discipline in the use of expert evidence in tax litigation.
Applications must be:
- precisely framed;
- anchored in the pleaded issues; and
- proportionate to what the Tribunal actually needs to decide.
A broad, multi-strand application is unlikely to succeed. It risks being seen as over-inclusive, insufficiently targeted, and inconsistent with the overriding objective.
The Upper Tribunal’s intervention is a reminder that expert evidence is a tool to assist the Tribunal on defined issues, where assistance is genuinely required. It is not a vehicle for expanding the scope of the dispute or assembling a broad body of material in the hope that volume will distract from, or compensate for, weaknesses in an underlying case.
Practical steps
If your business is involved in a tax dispute where expert evidence is being considered, you should assess critically whether it is genuinely required and whether it is the most effective way of supporting your case, weighing up the value it brings against the cost and delay involved.
If expert evidence is required, any application should be tightly scoped, properly justified and aligned with the Tribunal’s procedural expectations.
If you would like to discuss the use of expert evidence in a current matter or require support in any aspect of litigation, please contact us.