Nuclear Reactors and a £2 Billion Tax Claim: Why This High-Stakes Battle Was Labelled ‘Standard’
- Bryan Crawford
- 15 hours ago
- 5 min read
Case: NNB Generation Company (HPC) Limited v The Commissioners for His Majesty’s Revenue and Customs
Court: First-tier Tribunal (Tax Chamber)
Date of Judgement: 26 February 2026
Subject: Tax Procedure, specifically, an application to re-allocate an appeal to the "complex" category under Rule 23 of the First-tier Tribunal (Tax Chamber) Rules 2009
Issue: The central issue was whether NNB’s appeal against an HMRC information notice (issued regarding £2 billion in R&D allowance claims for Hinkley Point C) should be re-categorized from "standard" to "complex". This involved determining if the case met threshold requirements such as requiring lengthy or complex evidence, involving an important principle, or involving a large financial sum. A secondary issue was NNB's application for witness statements to be exchanged sequentially rather than simultaneously
Decision: The Tribunal refused the application to re-allocate the appeal to the complex category, ruling that none of the statutory threshold requirements were satisfied. The Tribunal also refused the application for sequential witness statements.
Executive Summary
On 26 February 2026, the First-tier Tribunal (Tax Chamber) issued a decision in the case of NNB Generation Company (HPC) Limited v The Commissioners for HMRC. The primary matter before Tribunal Judge Robin Vos was NNB's application to re-allocate its appeal against an HMRC information notice from the "standard" category to the "complex" category under Rule 23 of the Tribunal Rules.
The Tribunal refused the application, concluding that while the underlying tax dispute involving £2 billion in Research and Development (R&D) allowances for Hinkley Point C is undeniably complex, the specific appeal against the information notice did not meet the necessary threshold requirements. The Judge emphasized that the legal test for an information notice—whether documents are "reasonably required"—presents a relatively low hurdle that does not necessitate the lengthy or complex evidence required for a "complex" designation. Additionally, the Tribunal refused NNB’s application for the sequential exchange of witness statements, maintaining the standard requirement for simultaneous exchange.
The Nuclear Project Information Dispute
The appellant, NNB Generation Company (HPC) Limited ("NNB"), is responsible for the design, construction, and operation of the Hinkley Point C nuclear power plant. Since 2016, HMRC has been enquiring into NNB's claims for R&D allowances totalling approximately £2 billion.
The heart of the dispute involves these two opposing views:
NNB's "Single Project" Stance: NNB maintains that the entire design of the nuclear reactors at Hinkley Point C constitutes a single, unified project. They argue that this entire process represents a "single advance" in science or technology that qualifies as research and development
HMRC's "Sub-projects" Theory: HMRC is investigating whether the work is actually a series of distinct sub-projects. Their contention is that if the project is broken down, they can determine if only specific parts meet the statutory criteria for R&D—specifically, whether each part aims to achieve an advance by resolving scientific or technological uncertainty
In August 2023, HMRC issued an information notice requiring NNB to provide extensive documentation to investigate its 'sub-project' theory. NNB appealed this notice in April 2024, arguing the request was:
Irrelevant: Lacking a full understanding of the technical/scientific nature of the project.
Unclear: Lacking specific clarity in its requirements.
Duplicate: Requesting information already in HMRC's possession.
Disproportionate: Imposing unreasonable time and cost burdens.
The Purpose of Categorization
Under Rule 23 of the Tribunal Rules, cases are allocated to one of four categories: Default Paper, Basic, Standard, or Complex. NNB sought the "Complex" designation primarily to access the costs shifting regime, which would allow it to recover legal costs if successful, given its view that the information notice is "misconceived."
Analysis of Complex Categorization Requirements
Under Rule 23(4), a case may only be allocated as "Complex" if it meets at least one of three threshold requirements. The Tribunal analysed each in the context of the information notice appeal.
1. Lengthy or Complex Evidence or a Lengthy Hearing
The Tribunal determined that this gateway was not satisfied based on the following findings:
Nature of Evidence: While the nuclear engineering project is technically complex, the Tribunal’s role in an information notice appeal is "judicial monitoring." It only needs a "general understanding" of the science to determine if there is a "rational connection" between the request and the investigation.
Threshold of Proof: The burden is on HMRC to show information is "reasonably required," but the Judge noted this is not a "high hurdle."
Hearing Length: A hearing is generally considered "lengthy" if it exceeds five days. Despite NNB's estimate of five to six days, the Judge concluded the hearing would likely not exceed five days, as many of the 100+ requests could be considered in groups rather than individually.
2. Complex or Important Principle or Issue
NNB argued that the underlying subject matter and the novel legal point of whether HMRC can request information on a claim NNB has not made (HMRC’s "sub-project" theory) constituted a complex issue. The Tribunal rejected this:
The principles involved are the standard "reasonably required" tests common to all information notice appeals.
The "sub-project" inquiry is a factual matter of investigation, not a novel legal principle.
3. Large Financial Sum
Guidance defines a "large" sum as £750,000 or more in direct taxes.
Tax at Stake: An information notice appeal does not directly involve a potential tax liability, though the underlying investigation does.
Compliance Costs: NNB argued that the cost of compliance would be significant, but the Tribunal noted that NNB failed to provide any quantified evidence or estimates of these costs. Therefore, this requirement could not be met.
Decision on Witness Statements
Shortly before the hearing, NNB applied for sequential exchange of witness statements (HMRC serving first, followed by NNB).
NNB's Argument | HMRC's Counter-Argument |
As HMRC bears the burden of proof, NNB needs to understand HMRC’s position before responding. | There is no good reason to depart from simultaneous exchange; NNB must provide evidence for its own case. |
NNB needs to know if HMRC's position has changed after reviewing 175 newly provided documents. | Further delay is not in the interests of justice; NNB is attempting to achieve an extension through the "back door." |
The application was refused. The Judge noted that the ongoing review of documents should not "delay indefinitely" the hearing. However, the Judge "strongly encouraged" both parties to co-operate on a schedule identifying which information requests have already been satisfied to narrow the scope of witness evidence.
Summary of Key Legal Principles Applied
The decision reinforced several established principles regarding the Tribunal's discretion in case allocation:
Holistic Assessment: Following Dreams Plc v HMRC, the Tribunal takes a "holistic" approach to determining allocation, looking at all circumstances including the overriding objective of fairness.
Ordinary Sense of Complexity: As noted in Capital Air Services, a case meeting a threshold requirement might still be denied "Complex" status if it is not "complex in the ordinary sense of the word."
Standard vs. Complex: The "Standard" category (the third of four levels) is designed for difficult and challenging cases that do not reach the exceptional requirements of the "Complex" category.
Rational Connection: The test for "reasonably required" information is whether there is a rational connection to the investigation (Kotton v HMRC), a standard that simplifies the evidentiary requirements for the Tribunal.
Final Decision
The Tribunal refused the application to re-allocate the appeal to the complex category and refused the application for sequential witness statements. The appeal remains in the standard category, and witness statements are due for simultaneous exchange on 27 February 2026.
