Quick Summary: The High Income Child Benefit Charge generates more HMRC disputes than almost any other personal tax charge, largely because it catches people who never realised they owed it. If you have received a discovery assessment, a failure-to-notify penalty, or simply disagree with HMRC’s HICBC calculation, you have the right to challenge it — first through HMRC’s internal review (mandatory reconsideration) and, if unresolved, through the First-tier Tax Tribunal. The landmark Wilkes case found HMRC had no power to use discovery assessments for HICBC at all — though this was reversed by Finance Act 2022 for tax years 2021/22 onwards. Penalties for failing to notify HICBC liability can often be successfully challenged using the reasonable excuse defence, particularly where HMRC’s “nudge letters” were not received. This guide explains the entire dispute process in detail.

Table of Contents

1. Why HICBC Generates So Many Disputes
2. The Three Types of HICBC Dispute
3. Discovery Assessments: What They Are and How HMRC Uses Them
4. The Wilkes Case: How One Taxpayer Changed HICBC Law
5. Finance Act 2022: The Legislative Reversal
6. What This Means for Your Discovery Assessment in 2026
7. Time Limits for HMRC to Raise a HICBC Assessment
8. Failure to Notify Penalties Under Schedule 41
9. How Penalty Percentages Are Calculated
10. The Reasonable Excuse Defence: Complete Guide
11. Key Case Law: Belloul, Hextall, Harwood, and Barrett
12. When Ignorance of the Law Is (and Isn’t) a Reasonable Excuse
13. Step 1: Internal Review (Mandatory Reconsideration)
14. Step 2: Appealing to the First-tier Tax Tribunal
15. How to Prepare and Present Your Tribunal Case
16. Alternative Dispute Resolution (ADR)
17. Penalty Suspension and Reduction for Disclosure
18. Common Grounds for Successful HICBC Appeals
19. What Happens If Your Appeal Fails
20. Practical Checklist: Building Your Appeal
21. Frequently Asked Questions

Why HICBC Generates So Many Disputes

The High Income Child Benefit Charge has been one of the most disputed personal tax charges in the UK tax system since its introduction in January 2013. The structural reason is straightforward: HICBC is unusual among UK tax charges because liability can arise without the taxpayer ever realising it.

Unlike PAYE income tax, which is calculated and deducted automatically by an employer, HICBC requires the higher earner in a household to register for Self Assessment and declare the charge themselves — even if they have never filed a tax return before, even if they are not the person who actually claims or receives the child benefit, and even if their partner made the original claim without telling them their income had crossed the threshold.

This structural design — placing the registration burden on a person who may not even know child benefit is being claimed in their household — created the conditions for hundreds of thousands of “failure to notify” cases. The new system drew hundreds of thousands more people into the self-assessment system and created a large number of taxpayers who did not realise they were liable to the charge and so did not declare it until much later, potentially exposing themselves to penalties.

By 2021/22, the most recent year for which full statistics are available, 395,000 individuals paid a total of £460 million in HICBC liability. Within that population, a significant subset only became aware of their liability after receiving an HMRC compliance letter — sometimes years after the liability first arose — at which point assessments and penalties for multiple tax years can arrive simultaneously.

The current set of priorities for HMRC was reaffirmed in 2026 guidance: in previous years statistics on HICBC claims and tax receipts were collated with figures on penalties, appeals and reviews; they are now included within HMRC’s broader Child Benefit annual statistical release. This consolidation reflects the HICBC’s now-mature place within the standard Self Assessment compliance landscape, rather than treating it as a novel or separately tracked charge — a sign that, more than a decade after its introduction, HMRC has largely settled into routine processes for identifying, assessing, and where necessary litigating HICBC non-compliance.

This guide is written for two overlapping audiences: people who have already received an HMRC letter, discovery assessment, or penalty notice relating to HICBC and need to understand their options, and people who want to understand the dispute landscape in advance — including the major case law that has shaped how HMRC and the tribunals now approach these disputes. Both groups benefit from understanding not just the mechanics of how to lodge an appeal, but the substantive legal arguments that have succeeded and failed in real cases, because a well-targeted appeal grounded in the right legal arguments has a materially better chance of success than a generic objection to the unfairness of the charge.

The Three Types of HICBC Dispute

Before addressing the detailed law, it helps to separate the three distinct types of HICBC dispute, because the correct response differs for each.

Many taxpayers facing an HMRC HICBC letter are dealing with two or even all three of these simultaneously — an assessment for unpaid HICBC across several tax years, plus a failure-to-notify penalty calculated as a percentage of that liability. Understanding which type of challenge applies to which part of the letter is the first step in building an effective response.

Discovery Assessments: What They Are and How HMRC Uses Them

A discovery assessment is a tool that allows HMRC to assess additional tax outside the normal Self Assessment process, used when HMRC “discovers” that tax which should have been assessed has not been. For HICBC purposes, this is the primary mechanism HMRC has used to collect the charge from taxpayers who did not register for Self Assessment and declare it themselves.

The legal basis sits in section 29 of the Taxes Management Act 1970 (TMA 1970). The provision allows HMRC, within statutory time limits, to assess income tax that “ought to have been assessed” where it has not been. Receiving an HMRC discovery assessment is alarming. It means HMRC believes you have paid insufficient tax, and it can arrive years after you filed your return, without warning. However, a discovery assessment is not automatically valid. The law imposes strict conditions on HMRC’s power to issue one, and many assessments are successfully challenged or overturned on appeal.

For HICBC specifically, the question of whether HMRC actually has the legal power to use discovery assessments became the subject of one of the most significant tax tribunal cases of the past decade.

Why HICBC Sat Uneasily Within the Discovery Assessment Framework

The discovery assessment mechanism was originally designed for situations where a taxpayer’s income had been under-assessed — for example, undeclared earnings, unreported investment income, or an error in a filed Self Assessment return. HICBC does not fit naturally into this framework because it is not, strictly speaking, a tax on income. It is what tax lawyers call a “free-standing charge” — a separate liability calculated by reference to child benefit received, layered onto the tax system, but not itself a form of income that has been under-assessed in the conventional sense.

This technical distinction is exactly what the Wilkes litigation turned on, and it explains why HMRC needed a specific legislative fix (Finance Act 2022) rather than simply continuing to rely on its existing discovery powers once the courts ruled against it. The episode is a useful illustration of how a charge introduced for one policy purpose (recovering child benefit from higher earners) can create unanticipated complications when bolted onto a tax administration system designed around different assumptions about what counts as “income.”

The Wilkes Case: How One Taxpayer Changed HICBC Law

In November 2018, HMRC notified Jason Wilkes that he might be liable to pay the HICBC from 2013 onwards. Wilkes checked his position and told HMRC that he agreed he was liable, at which point HMRC issued him with a discovery assessment for the underpaid tax. Wilkes appealed against the assessments via the First-tier Tribunal — not disputing that he owed the HICBC, but disputing HMRC’s legal power to collect it via a discovery assessment in his particular circumstances.

The case worked its way through three levels of the UK tax justice system:

The legal reasoning was technical but consequential: the Upper Tribunal decided that HMRC has no power to issue a “Discovery Assessment” in respect of the HICBC to taxpayers who had not filed a Self-Assessment Tax Return. The Upper Tribunal accepted that the individual in question was still liable to HICBC as a matter of substantive tax law — but concluded the assessments themselves had not been validly raised, because the procedural mechanism HMRC used to collect the tax was not legally available for this type of charge.

The Scale of the Implications

Following the Upper Tribunal’s initial ruling in 2020, lawyers were quick to identify the scale of the potential fallout. Hundreds of thousands of taxpayers could have grounds to appeal HMRC charges after the landmark child benefit case, lawyers claimed. As HMRC has lost its appeal, lawyers argued, it meant they were wrong to impose the HICBC by Discovery Assessments on hundreds of thousands of UK taxpayers subject to HICBC not filing self-assessment tax returns.

Finance Act 2022: The Legislative Reversal

HMRC did not accept the implications of losing Wilkes lying down. While appealing the decision through the courts (ultimately unsuccessfully, as the Court of Appeal also found against HMRC), the government simultaneously legislated to reverse the practical effect of the ruling going forward.

Section 97 of the Finance Act 2022 amended section 29 of TMA 1970 to provide for a discovery assessment to be issued where “an amount of income tax… ought to have been assessed but has not been assessed.” This reversed the decision in Wilkes, and allowed HMRC to make discovery assessments in relation to the HICBC. These amendments apply to the tax year 2021/22 and subsequent tax years.

Crucially, the legislation also has retrospective effect for discovery assessments which have already been issued — meaning that assessments issued before the law changed, for historic tax years, were also validated by the new provision, except in narrow circumstances.

The Critical Carve-Out: Appeals Made Before 30 June 2021

The retrospective validation does not apply to taxpayers who had already appealed their discovery assessment using Wilkes-type grounds before 30 June 2021. If you fall into this narrow category — having lodged an appeal on the basis that HMRC lacked power to issue the assessment, before that specific date — your appeal may still have a live Wilkes-based challenge available, depending on your specific circumstances and tribunal progress. This is a highly technical area and anyone in this position should seek specialist tax advice immediately, as the window to rely on this protection is narrow and case-specific.

For everyone else — the vast majority of taxpayers — Finance Act 2022 closed off the Wilkes argument as a general defence against HICBC discovery assessments from 2021/22 onwards, and largely retrospectively as well.

What This Means for Your Discovery Assessment in 2026

If you receive a HICBC discovery assessment in 2026, the Wilkes argument — “HMRC has no power to issue this assessment at all” — is no longer available as a general defence for the vast majority of cases, because Finance Act 2022 has retrospectively validated HMRC’s power to use discovery assessments for HICBC.

This does not mean discovery assessments cannot be challenged. It means the grounds for challenge have shifted away from the pure “no power to assess” argument toward:

1. Time limit challenges — was the assessment issued within the statutory time limit? (See next section)
2. Calculation challenges — is the adjusted net income figure correct? Is the child benefit amount correct?
3. Penalty challenges — even if the underlying tax is correctly assessed, was the penalty correctly calculated, and does a reasonable excuse apply?
4. The narrow pre-30 June 2021 carve-out — for a small number of cases only

A 2026 specialist guide to discovery assessments confirms the current landscape: discovery assessment appeals are technically demanding. The applicable statute, the relevant case law, and the procedural rules of the First-tier Tax Tribunal all require specialist knowledge.

Time Limits for HMRC to Raise a HICBC Assessment

The time limit within which HMRC can raise a discovery assessment depends on the taxpayer’s behaviour — this is one of the most important practical facts in any HICBC dispute, because many cases turn on whether HMRC acted within time.

HICBC cases are typically pursued under the failure to notify provisions (section 7 TMA 1970), which carry the long 20-year time limit — but critically, this 20-year window only applies in the absence of a reasonable excuse. HMRC can raise HICBC discovery assessments within 4 years or, if due to failure to notify (section 7 TMA), within 20 years, unless reasonable excuse under section 118(2) TMA.

This is why the reasonable excuse defence is so significant in HICBC disputes: establishing a reasonable excuse does not just reduce or eliminate a penalty — it can also mean HMRC was out of time to raise the underlying assessment at all, because the extended 20-year window only applies where there is no reasonable excuse for the failure to notify.

Failure to Notify Penalties Under Schedule 41

Separate from the underlying HICBC tax liability, HMRC frequently imposes a failure to notify penalty under Schedule 41 of the Finance Act 2008. This penalty applies specifically to the obligation to notify chargeability to income tax under section 7 TMA 1970 — the requirement to register for Self Assessment by 5 October following the end of the tax year in which HICBC liability first arose.

Failure to notify penalties apply where taxpayers fail to notify HMRC on time of circumstances concerning their tax liability, including when they first become liable to pay certain taxes. Similar to penalties for inaccuracy, there are degrees of culpability, with different penalty ranges depending on the taxpayer’s behaviour, and reductions available for disclosure. Penalties are not imposed in relation to non-deliberate failures where HMRC are satisfied that there is a reasonable excuse.

Behaviour Categories for Failure to Notify

The overwhelming majority of HICBC failure to notify cases fall into the “non-deliberate” category — taxpayers who simply did not know about the charge, rather than those who knowingly avoided declaring it. This matters enormously for the available penalty range and for the reasonable excuse defence.

How Penalty Percentages Are Calculated

Potential Lost Revenue (PLR)

The penalty is calculated as a percentage of the Potential Lost Revenue — not simply the HICBC amount itself. In cases of failure to notify liability, the Potential Lost Revenue (PLR) is defined as any income tax to which someone is liable and which remains unpaid by 31 January following the end of the tax year. The PLR does not equate to the amount charged by an assessment — assessments are simply a means of collecting tax whose liability has already arisen.

This distinction matters in disputes: even where a discovery assessment itself might be challenged on procedural grounds, the underlying penalty can still be valid as long as there is PLR — because the penalty’s validity does not depend on the assessment’s validity. The Upper Tribunal in a related case refused to be drawn on whether the assessments were valid since the penalty was valid regardless of the existence of the assessments.

The Reduction for Disclosure

Penalties can be substantially reduced where the taxpayer discloses the liability to HMRC, with the size of the reduction depending on whether disclosure was prompted (HMRC contacted you first) or unprompted (you came forward first), and on the quality of cooperation — “telling, helping, and giving” access to records.

Worked example from a real case: Mr Barrett was liable to the HICBC for tax year 2018/19. He failed to notify HMRC by the 5 October 2019 deadline. HMRC charged a penalty of 20%, on the basis that the behaviour was not deliberate, disclosure was prompted, and giving the maximum reduction for telling, helping and giving — bringing the penalty down from the maximum 30% non-deliberate rate to 20% in recognition of his full cooperation once contacted.

The Reasonable Excuse Defence: Complete Guide

The reasonable excuse defence is the single most important tool available to taxpayers disputing HICBC penalties. Critically, reasonable excuse negates penalty liability entirely where established — it is not merely a mitigating factor but a complete defence.

The Legal Test

The leading case on reasonable excuse, Christine Perrin v HMRC [2018] UKUT 156, sets out the framework tribunals must apply. Reasonable excuse for failure to notify is assessed objectively, considering the taxpayer’s knowledge, acts, omissions, and circumstances. The tribunal asks: would a prudent and reasonable taxpayer, exercising reasonable foresight and due diligence, having proper regard for their responsibilities under the Taxes Acts, have failed to notify in these circumstances?

Reasonable Excuse Is Not a Fixed List

There is no exhaustive list of what constitutes a reasonable excuse — it is assessed case by case against the objective standard above. However, certain factual patterns recur frequently in HICBC cases and have produced consistent (though not universal) tribunal outcomes, discussed in the case law section below.

What Does NOT Usually Count

• Simply being busy or having a demanding job
• Relying on a general belief that “someone would have told me” without specific facts supporting that belief
• Knowing about the HICBC in principle but assuming it didn’t apply without checking

What CAN Count — Subject to Specific Facts

• Not receiving HMRC’s compliance letters (genuinely, due to an address error)
• A partner claiming child benefit without informing the higher earner, combined with no HMRC communication reaching the higher earner
• Reliance on an accountant or agent who failed to advise on HICBC, in certain circumstances (Schedule 41, paragraph 21 addresses this specifically)
• Genuine and objectively reasonable lack of awareness of the law itself, in the right factual circumstances

Key Case Law: Belloul, Hextall, Harwood, and Barrett

These four First-tier Tribunal cases form the backbone of practical understanding of how reasonable excuse operates in HICBC disputes. They are not binding precedent on other tribunals in the strict sense, but they are highly persuasive and frequently cited.

Belloul v HMRC — Ignorance of the Law as Reasonable Excuse

Bachir Belloul failed to notify HMRC of his HICBC liability for three tax years (2013/14 to 2015/16). HMRC wrote to him in October 2017 advising he might be liable and had not registered for Self Assessment. Belloul said he was unaware of his liability until that letter. HMRC argued ignorance of the law was not a reasonable excuse, citing established case law that it is for individuals to take steps to understand the law and how it applies to them.

The tribunal disagreed. The appeal was allowed and the penalties quashed. The key finding: ignorance of the law was a reasonable excuse for failing to notify, and he was not required to “rummage” through all of HMRC’s information sources to discover an obligation he had no reason to suspect existed.

Hextall v HMRC — The Absence of a Targeted Campaign

The tribunal in this case placed significant weight on the absence of any subsequent communications, either by way of a general campaign aimed at those in Mr Hextall’s position, or direct correspondence, in concluding that it was objectively reasonable for him to have been unaware of the requirement to notify HMRC for the 2015/16 and 2016/17 tax years. Because nothing changed in his awareness until HMRC’s “nudge letter” arrived in November 2019, his reasonable excuse continued throughout that period, and the resulting assessments for those years were found to be out of time.

This case illustrates the time-limit interaction discussed earlier: a successful reasonable excuse defence did not just remove the penalty — it also meant HMRC’s extended assessment window did not apply, making the assessment itself invalid for being out of time.

Harwood v HMRC — A Partial Success

Jonathan Harwood appealed assessments and penalties relating to HICBC for tax years 2016/17 to 2018/19, totalling £5,752 in assessments and £1,150.40 in penalties. His wife had claimed child benefit; his income exceeded £50,000 (the threshold at the time) due to salary and car benefit valuations. He did not receive HMRC’s nudge and final reminder letters — they had been sent to an incorrect address.

The tribunal found he had a reasonable excuse for not knowing earlier and cancelled some of the tax assessment and all of the penalties — but the appeal against the underlying HICBC assessments for the later years (2017/18 and 2018/19) was ultimately dismissed, illustrating that reasonable excuse arguments can succeed for penalties and earlier years while still failing for later periods once awareness should reasonably have arisen.

Barrett v HMRC — A Narrow, Low-Value Win

Mr Barrett accepted he was liable for the underlying HICBC itself but disputed only the £182.40 penalty, on the basis that not receiving HMRC’s letters was a reasonable excuse for his failure to notify. This case is a useful reminder that HICBC appeals do not need to be high-value to be worth pursuing — even modest penalty amounts can be successfully challenged where the facts support a reasonable excuse, and the administrative cost to HMRC of contesting small claims means many are conceded or lightly defended.

When Ignorance of the Law Is (and Isn’t) a Reasonable Excuse

The interaction between “ignorance of the law” and reasonable excuse is the most contested legal question in HICBC disputes, and the case law is genuinely mixed — outcomes depend heavily on the specific facts of each case rather than a blanket rule.

Factors That Tend to Support Reasonable Excuse

• No HMRC compliance letters were sent, or they were sent to a wrong/old address
• No general public information campaign reached the specific taxpayer’s circumstances at the relevant time
• The taxpayer’s income only exceeded the threshold due to non-obvious elements (bonuses, benefits in kind, car allowances) that they might not naturally associate with “income” for HICBC purposes
• The taxpayer was not the person who claimed child benefit and had no reason to know their partner was claiming it
• The taxpayer took reasonably prompt action once they did become aware

Factors That Tend to Undermine Reasonable Excuse

• The taxpayer received HMRC’s nudge letters or general HICBC public information at the relevant time
• The taxpayer’s own Self Assessment return process (if already in Self Assessment for other reasons) included relevant questions about child benefit that were not answered accurately
• A significant period elapsed between when HMRC contacted the taxpayer and when they acted
• The taxpayer was a higher earner with sophisticated financial affairs where the tribunal considers it less plausible they were unaware

Information regarding the HICBC was also available on HMRC’s website from the outset, and HMRC has consistently argued — sometimes successfully, sometimes not — that the burden falls on individuals to take steps to understand changes in tax law that affect them. The tribunal’s task in each case is to weigh this general principle against the specific facts: what did this particular taxpayer know, what steps would have been objectively reasonable for them to take, and did they take those steps.

Step 1: Internal Review (Mandatory Reconsideration)

Before proceeding to the Tribunal, you may request an HMRC internal review. This is conducted by an officer not previously involved in your case. This step is sometimes called a statutory review or mandatory reconsideration, and it is generally a prerequisite (or at minimum, a highly advisable first step) before tribunal proceedings.

How to Request a Review

1. Respond in writing to the assessment or penalty notice within 30 days of the date of the decision
2. State clearly that you are appealing and request an internal review
3. Set out your grounds of appeal — the specific legal or factual basis for disputing the assessment or penalty
4. Provide supporting evidence (correspondence records, address history, employment records, etc.)

An appeal can be made to HMRC in writing without any technical formalities — there is no prescribed form for the initial appeal to HMRC itself, though clarity and specificity in your grounds significantly improve your prospects.

What Happens During the Review

A different HMRC officer, not previously involved in the case, reviews the original decision. They can uphold it, vary it, or cancel it. HMRC will issue a review conclusion letter setting out the outcome and reasoning. If you disagree with the review conclusion, you then have a further 30 days from the date of that letter to appeal to the Tribunal.

Step 2: Appealing to the First-tier Tax Tribunal

If the internal review does not resolve the matter in your favour, the next stage is an appeal to the First-tier Tribunal (Tax Chamber).

The Appeal Form and Deadline

The appeal is commenced by filing a Notice of Appeal with the Tribunal. An appeal to the Tribunal can be made using the appeal form available on the Tribunal’s website, and that should be straightforward to complete for most taxpayers, particularly in penalty-only disputes. The deadline is 30 days from the date of the review conclusion letter (or from the original decision if no review was requested).

What Happens If You Miss the Deadline

If you miss this deadline, the assessment becomes final unless you can persuade the First-tier Tribunal to admit a late appeal — a process that has become more flexible following recent case law on late appeals, though it remains a discretionary decision the tribunal may refuse. Acting promptly is always preferable to relying on a late appeal being admitted.

Burden of Proof

The appeal is commenced by filing a Notice of Appeal with the Tribunal. At the hearing, the burden of proving the assessment rests on HMRC for certain issues, but the taxpayer must actively make good their own grounds of challenge. In practice, this means: HMRC generally must establish that the tax was due and that any penalty behaviour categorisation is correct, while the taxpayer bears the practical burden of establishing facts supporting a reasonable excuse defence or a calculation error.

How to Prepare and Present Your Tribunal Case

Documentary Evidence to Gather

Whether to Use a Representative

You can represent yourself at the First-tier Tribunal — many taxpayers do, particularly in straightforward penalty disputes, and the Tribunal is designed to be accessible without legal representation. However, for cases involving multiple tax years, larger sums, or genuine legal complexity (such as residual Wilkes-type arguments for the narrow pre-30 June 2021 category), specialist tax representation is worth the cost. Early legal advice allows you to assess the strength of your position, identify the best grounds of challenge, and avoid making statements that could prejudice your case.

What the Tribunal Will Want to Know

Tribunals assessing reasonable excuse consistently focus on: what did you actually know and when; what would a reasonable person in your specific circumstances have done; and whether HMRC’s own conduct (sending letters to the wrong address, failing to run an effective public information campaign reaching people in your situation) contributed to your lack of awareness. Specific, well-evidenced answers to these questions consistently outperform general assertions of unfairness.

The Hearing Itself

First-tier Tribunal tax hearings are generally less formal than court proceedings, though they follow a structured process. Most HICBC appeals are heard in person at a regional tribunal venue, though paper-based determinations (without an oral hearing) and remote video hearings are both available options depending on the complexity of the case and the preferences of the parties. For straightforward penalty disputes turning primarily on documentary evidence — such as proof of an address change — a paper determination can be quicker and less stressful than an oral hearing, though it removes the opportunity to respond to questions from the tribunal panel in real time.

A typical hearing involves: an opening statement from each party (or simply submissions if unrepresented), examination of the documentary evidence, oral evidence from the taxpayer (and any witnesses) under questioning from the HMRC representative and the tribunal panel, and closing submissions. The tribunal panel — typically a single judge, sometimes with a lay member for certain case types — will issue a written decision, which may take several weeks or months to arrive after the hearing.

Costs

The First-tier Tribunal (Tax Chamber) generally operates on a “no costs” basis for most standard track cases — meaning that even if you lose, you will not usually be ordered to pay HMRC’s costs, and HMRC will not usually be ordered to pay yours if you win. This is an important feature that makes self-representation a genuinely viable option for many taxpayers, as the financial risk of an unsuccessful appeal is limited primarily to your own time and any fees paid to an adviser, rather than an adverse costs order.

Alternative Dispute Resolution (ADR)

For some HICBC disputes — particularly those involving genuine disagreement over facts rather than pure points of law — HMRC’s Alternative Dispute Resolution service offers a mediated route to resolution without proceeding to a full tribunal hearing. ADR involves an HMRC-trained mediator (not previously involved in the case) facilitating a discussion between the taxpayer and the HMRC caseworker to try to reach an agreed resolution.

ADR can be requested at various stages of a dispute, including during an ongoing tribunal appeal (with the tribunal’s agreement to pause proceedings). It is generally faster and less formal than a full tribunal hearing, though it is not available or appropriate for every type of dispute — disputes turning on a pure point of law (such as the legal scope of HMRC’s assessment powers) are generally not well suited to ADR, whereas factual disputes about reasonable excuse circumstances often are.

Penalty Suspension and Reduction for Disclosure

Suspension — Limited Availability for HICBC

HMRC can suspend a careless inaccuracy penalty for up to two years under paragraph 14 of Schedule 24, with conditions typically requiring improved record-keeping or compliance. Suspension is only available for careless penalties, not deliberate ones, and it is discretionary — HMRC can refuse to suspend. You can appeal HMRC’s refusal to suspend, or the conditions they set.

It is worth noting that Schedule 24 suspension provisions are most commonly associated with inaccuracy penalties rather than the failure-to-notify penalties (Schedule 41) most relevant to HICBC — but the same underlying logic of penalty mitigation through disclosure applies under Schedule 41’s own reduction mechanism.

The Schedule 41 Disclosure Reduction

Reductions for disclosure under Schedule 41, paragraph 12, operate on the “telling, helping, giving” framework:

This is why, in practice, taxpayers who receive an HMRC HICBC letter and respond promptly, honestly, and cooperatively — even if they ultimately owe the tax — typically see substantially lower penalties than those who delay or are uncooperative, regardless of whether a reasonable excuse argument ultimately succeeds.

Common Grounds for Successful HICBC Appeals

Drawing together the case law and statutory framework above, the most consistently successful grounds for HICBC appeals in 2026 are:

1. Reasonable excuse based on non-receipt of HMRC letters — particularly where an address change can be evidenced and HMRC sent correspondence to an old address
2. Reasonable excuse based on the absence of a targeted compliance campaign reaching the taxpayer’s specific circumstances during the relevant years, combined with prompt action once contacted
3. Time limit challenges — arguing the 4-year (or 6-year, for careless behaviour) time limit applied rather than the extended failure-to-notify window, because a reasonable excuse existed throughout the relevant period
4. Calculation errors — incorrect adjusted net income figures, incorrect child benefit amounts, or incorrect identification of which partner is the “higher earner”
5. Penalty percentage disputes — arguing for a lower behaviour categorisation (non-deliberate rather than careless) or a larger disclosure reduction than HMRC initially applied
6. The narrow pre-30 June 2021 Wilkes carve-out — for the small number of taxpayers who appealed on Wilkes grounds before that date

What is now largely unavailable: the general “HMRC has no power to issue any HICBC discovery assessment” argument, which Finance Act 2022 closed off retrospectively for the vast majority of cases.

HMRC’s Nudge Letter Campaigns: Why They Matter to Your Defence

Several of the case law examples above turn on whether a taxpayer received — or failed to receive — one of HMRC’s “nudge letters.” Understanding what these letters are and how HMRC’s compliance campaigns operate is directly relevant to building a reasonable excuse defence.

What Is a Nudge Letter

A nudge letter is a written communication HMRC sends to a taxpayer where data held by HMRC suggests they may have an undeclared tax liability, without HMRC necessarily having concluded that they definitely do. For HICBC, nudge letters have been sent in successive campaigns since 2013, generally triggered by HMRC’s data matching between PAYE income records and child benefit claim records held by the Child Benefit Office.

When HMRC’s systems identify a household where one partner’s PAYE income exceeds the HICBC threshold and the same household (or an address-linked household) has an active child benefit claim, this is flagged for a potential compliance letter. The letter typically invites the recipient to check their position and, if applicable, register for Self Assessment voluntarily before HMRC proceeds with a formal assessment.

Why Nudge Letter History Is Central to Many Successful Appeals

The case law pattern is consistent: where a taxpayer can show that no nudge letter (or any other targeted compliance communication) reached them before HMRC’s eventual discovery and assessment — particularly because of an address error, as in Harwood, or because the relevant compliance campaign simply had not yet reached people in their specific circumstances, as in Hextall — tribunals have repeatedly found this supports a reasonable excuse. The absence of a targeted campaign reaching the taxpayer’s circumstances, combined with no other realistic route to awareness, is treated as objectively significant.

Conversely, where HMRC can demonstrate that letters were sent to the taxpayer’s correct, current address and there is no good reason to doubt they were delivered, this significantly weakens a reasonable excuse argument based on lack of awareness, because the tribunal will generally infer that a letter correctly addressed and not returned as undelivered was likely received.

Practical Implication: Request Your HMRC Contact History

Anyone disputing a HICBC penalty on reasonable excuse grounds should request from HMRC (via a Subject Access Request under data protection law, or simply by asking your caseworker) a full record of what correspondence was sent to you, when, and to which address, for the tax years in dispute. This evidence is frequently decisive, and obtaining it early in the dispute process — rather than waiting until shortly before a tribunal hearing — gives you more time to identify any address discrepancies and gather corroborating evidence (such as old tenancy agreements, mail redirection records, or utility bills) showing where you actually lived during the relevant period.

What Happens If Your Appeal Fails

If the First-tier Tribunal upholds HMRC’s assessment and/or penalty, you have the following options:

1. Pay the assessed amount (with any agreed time-to-pay arrangement if needed — contact HMRC’s Payment Support Service)
2. Appeal to the Upper Tribunal, but only on a point of law (not simply because you disagree with the factual findings), and only with permission either from the First-tier Tribunal or the Upper Tribunal itself
3. Accept the outcome and ensure future compliance — register for Self Assessment promptly if your circumstances mean HICBC will continue to apply in future years

Interest accrues on unpaid HICBC liabilities and penalties from the original due date, so prolonged disputes that are ultimately unsuccessful can result in a larger final bill than the original assessment, due to accumulated interest. This is a relevant practical consideration when weighing whether to pursue an appeal with genuinely weak prospects versus negotiating a time-to-pay arrangement instead.

Why “It’s Unfair” Is Not, By Itself, a Winning Argument

A recurring theme across HICBC tribunal cases is taxpayers raising the structural unfairness of the charge itself — particularly the well-known anomaly that a single-earner household can be fully charged at a relatively modest income while a dual-earner household with a substantially higher combined income pays nothing. One taxpayer’s stated grounds of appeal included the argument that the HICBC is unfair for single income households, when dual income households can each earn just under the threshold without being liable for the HICBC.

Tribunals have been consistent in treating this argument, however valid as a matter of policy critique, as not a legal ground of appeal. The First-tier Tribunal does not have the power to strike down or disapply primary legislation on grounds of unfairness — its role is to apply the law as Parliament enacted it, not to rule on whether that law represents good policy. Taxpayers who raise only the structural unfairness argument, without separately establishing a reasonable excuse, a calculation error, or a procedural defect, will not succeed on that argument alone, however sympathetic the tribunal may be to the underlying point.

This does not mean the unfairness argument is irrelevant to making your case more broadly persuasive or to settlement discussions with HMRC outside the tribunal process — but as a strict legal matter, it cannot form the basis of a successful appeal. Taxpayers wishing to challenge the policy itself should direct that advocacy toward Parliament and the Treasury, via consultations, select committee evidence, or campaigning organisations — not the tax tribunal, which exists to apply the law, not to change it.

Practical Checklist: Building Your Appeal

• Identify exactly which tax years are covered by the assessment and penalty
• Establish for each year: was your adjusted net income actually above £60,000 (or the relevant historic threshold for that year)?
• Establish for each year: was child benefit actually being received in your household?
• Gather your address history for the relevant years and compare against where HMRC’s correspondence was sent
• Check whether you ever received any HICBC-related letters, nudge letters, or general HMRC communications, and when
• Calculate the Potential Lost Revenue independently and check it against HMRC’s figure
• Identify the behaviour category HMRC has applied (non-deliberate, careless, deliberate) and consider whether it is correct
• Check the disclosure reduction HMRC has applied and whether full cooperation could increase it
• Request the internal review in writing within 30 days, setting out clear grounds
• If unresolved, file the Notice of Appeal with the First-tier Tribunal within 30 days of the review conclusion
• Consider whether ADR is appropriate for your specific dispute
• Consider whether specialist tax representation is proportionate to the amounts and complexity involved

Frequently Asked Questions

Can I still appeal a HICBC discovery assessment using the Wilkes case?

For the vast majority of taxpayers, no — Finance Act 2022 retrospectively gave HMRC the power to issue HICBC discovery assessments, closing off the general Wilkes argument. A narrow exception exists for taxpayers who had already lodged a Wilkes-type appeal before 30 June 2021; specialist advice is needed to assess whether this applies to you.

What is a reasonable excuse for not notifying HMRC about HICBC?

A reasonable excuse is assessed objectively — would a prudent, reasonable taxpayer in your specific circumstances have failed to notify? Common successful grounds include not receiving HMRC’s compliance letters due to an address error, and the absence of any targeted communication reaching your specific circumstances before you became aware and acted promptly. Ignorance of the law itself has succeeded as a reasonable excuse in several tribunal cases, including Belloul.

How much can a HICBC failure to notify penalty be?

Up to 30% of the Potential Lost Revenue for non-deliberate behaviour (the most common category), reducible based on disclosure quality. Deliberate behaviour can attract penalties up to 70%, and deliberate and concealed behaviour up to 100% — though these higher categories are rare in HICBC cases.

How long does HMRC have to assess HICBC liability?

Generally 4 years from the end of the relevant tax year for non-careless cases, 6 years for careless behaviour, and up to 20 years for failure to notify — unless a reasonable excuse existed throughout, in which case the extended window does not apply and the standard 4-year limit may govern instead.

What is the first step in disputing a HICBC assessment or penalty?

Request an HMRC internal review (statutory review) in writing within 30 days of the decision, setting out your grounds clearly. If the review does not resolve matters in your favour, you can then appeal to the First-tier Tribunal (Tax Chamber) within 30 days of the review conclusion.

Do I need a lawyer or accountant to appeal a HICBC penalty?

Not necessarily. Many taxpayers represent themselves successfully at the First-tier Tribunal, particularly in straightforward penalty disputes. For complex cases involving multiple tax years, larger sums, or residual legal questions, specialist tax representation is advisable and can materially improve your prospects.

Can I dispute just the penalty and accept the underlying HICBC tax?

Yes. Several successful cases involved taxpayers who accepted they owed the underlying HICBC but disputed only the penalty on reasonable excuse grounds — this is a common and often successful approach, as seen in cases like Barrett v HMRC.

What happens if HMRC sent letters to my old address?

This is one of the strongest factual grounds for a reasonable excuse defence, as demonstrated in Harwood v HMRC, where letters sent to an incorrect address contributed to the tribunal finding a reasonable excuse and cancelling the associated penalties.

Quick Reference: HICBC Dispute Timeline

Related Reading

• High Income Child Benefit Charge 2025/26: The Hidden Tax Trap Costing Families Thousands
• Child Benefit Rates 2026: Complete UK Guide
• Child Benefit Eligibility Rules 2026: The Complete UK Guide
• HMRC Penalties: How They Work and How to Appeal
• How to File a Self Assessment Tax Return 2025/26

Information correct as of June 2026 based on current legislation and reported case law. Tax dispute resolution depends heavily on individual facts and circumstances. This article does not constitute legal or tax advice. For a HICBC dispute of any significant value or complexity, consult a qualified tax adviser, accountant, or tax solicitor. HMRC Self Assessment helpline: 0300 200 3310. The First-tier Tribunal (Tax Chamber) appeal form and guidance is available at gov.uk/tax-tribunal.