The Upper Tribunal will consider whether retrospective legislation introduced after the Court of Appeal’s decision in Wilkes can validate HMRC’s discovery assessments against ordinary PAYE taxpayers. The appeals raise significant questions about legal certainty, access to justice and the interpretation of retrospective tax legislation.

London, Tuesday 21 July 2026. Collyer Bristow LLP is acting pro bono in two joined Upper Tribunal appeals concerning HMRC’s use of discovery assessments to collect the High-Income Child Benefit Charge (HICBC) from PAYE taxpayers.

The appeals, Niewiarowski v HMRC and HMRC v Fera, will be heard in the Upper Tribunal, Tax and Chancery Chamber, on Tuesday 21 and Wednesday 22 July 2026.

Introduced in 2013, HICBC is intended to means-test Child Benefit by clawing it back through the tax system where one member of a household has income above a specified threshold. The charge is unusual because Child Benefit can be paid to one person while the tax liability falls on another person in the household. That is what happened in both of these appeals: Child Benefit was paid to the taxpayers’ wives, but HMRC assessed Mr Fera and Mr Niewiarowski to HICBC.

These appeals concern ordinary PAYE taxpayers who, apart from HICBC, were not required to file self-assessment tax returns, had not been told by HMRC to file tax returns for the relevant years, and who were unaware of any need to notify HMRC about HICBC. HMRC still sought to collect HICBC from them by issuing discovery assessments. In Mr Niewiarowski’s case, as with many other taxpayers in a similar position, they levied penalties for ‘careless’ conduct too.

That assessment route is central to the appeals. In HMRC v Wilkes (in which Collyer Bristow also acted pro bono), the First-tier Tribunal, the Upper Tribunal and the Court of Appeal all unanimously decided that HMRC could not use discovery assessments to assess HICBC because the charge was not itself “income” for the purposes of the legislation. As a result, HICBC discovery assessments which had been issued by HMRC were invalid: HMRC had exceeded their powers in issuing them.

But before the Court of Appeal released its judgment, Parliament enacted section 97 of the Finance Act 2022, which widened HMRC’s discovery assessment powers to deal with the issue raised in Wilkes.

Insofar as section 97 operated prospectively in the usual way, there was nothing untoward in that.  However, unusually and very controversially, Parliament gave those changes retrospective effect in certain circumstances, affecting the rights of taxpayers whose appeals against HICBC discovery assessments had already been notified to HMRC and the First-tier Tribunal. The central issue in Niewiarowski and Fera is whether this retrospective legislation validates the assessments issued to these taxpayers. The taxpayers say it does not; HMRC disagree.

James Austen, Partner at Collyer Bristow LLP, commented: “These appeals raise a fundamental question about fairness in the tax system. The Court of Appeal rejected HMRC’s position in Wilkes, and the Government legislated retrospectively to limit the benefit of that judgment for other taxpayers. These cases ask how far that retrospective effect really goes.

The taxpayers’ case is simple: Parliament did not say that appellants – especially unrepresented taxpayers without specialist tax/legal knowledge – had to identify the Wilkes point in precise technical terms to avoid the retrospective change. Many affected individuals were basic-rate PAYE taxpayers who had never been required to file self-assessment returns and had no reason to think they needed tax advice. HMRC’s interpretation risks introducing a two-tier justice system in which wealthy taxpayers who can afford the best professional advice would get to escape HICBC discovery assessments, but everyone else, including ordinary taxpayers with modest incomes and no access to a specialist lawyer, would be left exposed on a technicality.

One fundamental principle of the rule of law as it applies in England is that laws should not ordinarily impact on citizens’ rights after the event. So retrospective tax changes should not have any wider application than absolutely necessary. Retrospective tax legislation offends the rule of law because it changes taxpayers’ legal position when they are not able to do anything about it. In many cases, that can be profoundly unfair. Previously, retrospective tax laws were reserved for countering aggressive tax avoidance schemes. So it is concerning when HMRC say, as they do in these cases, that it should be given an expansive interpretation to defeat appeals by ordinary taxpayers against HICBC discovery assessments.

These appeals raise important questions about legal certainty, access to justice and the fair treatment of unrepresented taxpayers. In addition to HICBC discovery assessments, their outcome potentially has implications for the Government’s approach to retrospective tax measures in general, and the rules that Tribunals and Courts must adopt when considering how to give effect to them.”

In addition, these appeals are important in (again) shining a light on the broader unfairness issues with the HICBC regime as a whole, which the Government compounded when it doubled down and took the unprecedented steps of issuing retrospective legislation to cure a defect in its original scheme.

As was the case in Wilkes, Collyer Bristow LLP is pleased to act pro bono for these taxpayers, in recognition of the wider public significance of the issues at stake. The team is led by James Austen, a Partner in the Private Wealth Disputes team, assisted by Camilla Brown, a Trainee Solicitor. They are instructing Marika Lemos KC and Matthew Bignell of Counsel (both practicing from Devereux Chambers), who are also acting pro bono.

Notes to Editors:

Further important context:

The taxpayers say the retrospective provisions of section 97 Finance Act 2022 should not be interpreted widely so as to defeat appeals brought by unrepresented taxpayers who had challenged HICBC discovery assessments as being invalid, but who had not identified the technical Wilkes point in specialist terminology.

The central question for the Upper Tribunal is what Parliament meant when it ring-fenced certain existing HICBC appeals from the retrospective effect of section 97 where the relevant invalidity issue had been “raised” by 30 June 2021. HMRC interpret that section as requiring the issue to be raised expressly or specifically. The taxpayers say that approach is too broad, unfair and inconsistent with the wording Parliament actually used. Instead, they argue that an appeal expressed in general terms against the validity of HICBC discovery assessments is all that is needed to fall outside the retrospective effect of section 97, because the words used by Parliament do not require anything more.

The taxpayers’ argument is advanced on conventional English law principles of statutory interpretation.  One interesting – and rare – aspect of the appeals is that it gives the Upper Tribunal the opportunity to set out in a binding judgment how the Tax Tribunals are to approach questions about the construction of retrospective tax legislation.

For media enquiries, please contact:

Collyer Bristow LLP: christopher.wilsher@collyerbristow.com

Byfield Consultancy: jessica@byfieldconsultancy.com