Reasonable Excuse HMRC Penalty: What Actually Qualifies
HMRC rejects most reasonable excuse claims. Here's what the law actually says qualifies, what doesn't, and how sole traders can build a winning case.
HMRC issued over 600,000 Self Assessment penalty notices in 2022/23 alone. How many of those taxpayers knew they could challenge the charge with a reasonable excuse? Far fewer than should have.
The phrase "reasonable excuse" appears in tax legislation as if it were straightforward. It is not. HMRC's own guidance runs to thousands of words, tribunal cases have contradicted each other for decades, and the definition remains deliberately vague. That vagueness costs sole traders real money, because most people either never appeal or abandon a valid claim the moment HMRC pushes back.
This post is not another overview of how to file a Self Assessment return on time. It is a hard look at what "reasonable excuse" actually means under UK tax law, which scenarios HMRC will and will not accept, and how to present a claim that survives scrutiny.
- HMRC has no statutory definition of reasonable excuse; tribunals decide case by case, which means the argument you make matters enormously.
- Ignorance of the law is not a reasonable excuse, but genuine reliance on professional advice that turned out to be wrong often is.
- A serious or unexpected illness, a bereavement, or a genuine technical failure can all qualify, but only if you act promptly once the obstacle is removed.
- HMRC rejects most first-time reasonable excuse claims. A well-structured appeal letter, referencing the correct legislation and tribunal precedents, dramatically improves your odds.
- Under MTD, the points-based penalty system creates new grounds for reasonable excuse appeals that did not exist under the old regime.
- Reasonable Excuse
- A legal concept in UK tax law that allows a taxpayer to avoid a penalty if they had a genuine reason for failing to meet a deadline. There is no statutory definition; HMRC and tax tribunals assess each case on its specific facts, asking whether a responsible taxpayer exercising reasonable care would have failed in the same circumstances.
The Legal Framework HMRC Does Not Advertise
Section 118(2) of the Taxes Management Act 1970 is the provision sole traders should know. It states that a person shall be deemed not to have failed to do something if they had a reasonable excuse for the failure and, once the excuse ceased, acted without unreasonable delay.
That second clause is the one most people miss. You cannot claim reasonable excuse if you recovered from a serious illness in February and still did not file until October. The excuse has to explain the entire period of delay, and once it ends, the clock restarts.
For Making Tax Digital penalties specifically, Schedule 55 of the Finance Act 2009 and the newer points-based regime under Schedule 24 of the Finance Act 2021 both preserve the reasonable excuse defence. If you have already read MTD Late Payment Penalty: How the Points System Works, you will know that accumulating points triggers fixed penalties. Reasonable excuse, if accepted, wipes those points and the associated charge.
What HMRC Will Actually Accept
There is no master list of approved excuses. But decades of First-tier Tribunal decisions have produced a reliable picture of what works.
Serious illness or mental health crisis
This is the most commonly accepted ground, and also the most commonly mishandled. A bad cold does not qualify. A hospitalisation, a serious mental health episode, or a condition that genuinely prevented you from accessing your records or making decisions does.
The key case here is Christine Perrin v HMRC [2018] UKUT 156, where the Upper Tribunal confirmed that the test is objective: would a reasonable taxpayer in the same situation have also failed to file? Not "was the taxpayer upset" but "was the failure genuinely unavoidable?"
Practically: keep a GP letter, hospital discharge summary, or consultant's note. HMRC caseworkers respond to documentation. A letter saying "I was unwell" without evidence will be rejected at first instance.
Bereavement
The death of a close relative or partner, particularly one who handled household finances, is regularly accepted. Again, timing matters. If your spouse died in November and you filed four months after the January deadline, you need to explain why four months was not enough time, or why the January deadline itself fell within the acute period of grief and administrative chaos that a bereavement causes.
Genuine reliance on professional advice
If you hired an accountant, told them everything they needed, and they still filed late or incorrectly, you may have a reasonable excuse even though the professional's failure is technically your problem. The tribunal in Rowland v HMRC [2006] STC (SCD) 536 established that acting in good faith on professional advice can qualify, provided you took reasonable steps to find a competent adviser and gave them accurate information.
This matters specifically for sole traders who ask Can My Accountant Do MTD for Me?. The answer is largely yes, but the legal responsibility still sits with you. If your accountant misses an MTD quarterly deadline, your reasonable excuse claim needs to show you did everything reasonably expected of you as the client.
Technical failure of HMRC's own systems
This one is consistently overlooked. If HMRC's online services were unavailable and you attempted to file on time, that is a reasonable excuse. HMRC publishes service status notices and you should screenshot the error message the moment it appears. The phrase to include in your appeal is that you made a genuine and timely attempt to comply and the failure was caused by a third-party system outside your control.
The same logic applies to MTD-compatible software failures. If your software provider's servers went down during a quarterly submission window and you can evidence that, HMRC should accept it. See Automatic Receipt Scanning Tax UK: Does It Actually Work? for context on just how often software promises exceed software delivery.
What HMRC Will Reject, Every Time
Knowing what does not work is as valuable as knowing what does.
"I didn't know I had to file"
Ignorance of a filing obligation is almost never accepted. The tribunal has repeatedly held that sole traders are responsible for understanding their obligations, or for seeking advice if they are unsure. If you are in business, HMRC expects you to know that Self Assessment exists.
"I couldn't afford an accountant"
Financial difficulty does not excuse a failure to file. It may, in limited circumstances, explain a failure to pay, but the two are separate issues. HMRC distinguishes filing penalties (for not submitting) from payment penalties (for not paying the tax owed). You can almost always file a return even if you cannot pay the resulting liability.
"I was busy"
Pressure of work, a demanding contract, or being the only person running your business are not reasonable excuses. The tribunal has been blunt on this point. Every sole trader is busy. The obligation to file does not pause because your schedule is difficult.
"I forgot"
For the avoidance of doubt: forgetting is not a reasonable excuse. HMRC sends multiple reminders, and the January 31st Self Assessment deadline has not changed since 1997.
The Argument Structure That Actually Works
If you believe you have a valid reasonable excuse, the quality of your appeal letter matters more than most people realise. HMRC caseworkers process hundreds of appeals. A clearly structured argument citing the correct legislation will receive more serious consideration than a narrative complaint.
Include the following in every appeal:
- The specific penalty reference number from the notice.
- The legal basis for your appeal: section 118(2) TMA 1970 for Self Assessment, or the relevant schedule for MTD penalties.
- A clear timeline: when the filing obligation arose, when the excuse began, what the nature of the excuse was, when it ceased, and when you actually filed.
- Supporting evidence: medical letters, death certificates, screenshots of HMRC system errors, correspondence with your accountant.
- A closing statement that you acted without unreasonable delay once the excuse ceased.
You must submit your appeal within 30 days of receiving the penalty notice. Miss that window and you will need to argue for a late appeal separately, which requires its own justification.
For the mechanics of escalating beyond HMRC's initial decision, How to Appeal an HMRC Penalty and Actually Win covers the tribunal route in detail.
Reasonable Excuse Under MTD: New Rules, New Opportunities
Making Tax Digital for Income Tax, which applies to sole traders and landlords with income over £50,000 from April 2026, introduces a points-based penalty system. Each missed quarterly update earns one point. Four points triggers a £200 penalty. Further missed submissions add £200 each.
Reasonable excuse applies at two levels under this system. First, you can appeal an individual point, arguing the missed submission had a valid excuse. If accepted, the point is removed and does not count towards the threshold. Second, if the threshold has already been reached and a penalty issued, you can appeal the penalty itself.
This creates a window that did not exist under annual filing. A sole trader who misses one quarterly update due to illness, appeals successfully, and files the remaining three on time will never reach the four-point threshold. The system is harsher in structure but offers more intervention points than the old annual deadline.
If you are unsure whether the MTD points system applies to your situation yet, check MTD Penalty Exemptions: Who Actually Qualifies for the income thresholds and exclusion criteria.
A Concrete Scenario: Marcus the Electrician
Marcus is a self-employed electrician earning £62,000 a year. In December 2025, his father dies unexpectedly. Marcus handles the estate administration, funeral arrangements, and continued taking on work because he is a sole trader with no one to cover his jobs.
January 31st passes. Marcus files his Self Assessment on March 15th, six weeks late. He receives a £100 penalty notice.
Marcus has a strong reasonable excuse claim. His father died during the acute filing period, the bereavement involved direct estate administration duties that are documented, and he filed within a reasonable timeframe after the immediate crisis resolved.
His appeal letter should:
- Reference section 118(2) TMA 1970
- State the date of death and provide a copy of the death certificate
- Explain that he was the sole person managing the estate and has letters from the probate process to evidence this
- Note that he filed on 15 March, the first point at which he was able to address outstanding administrative obligations
- Request cancellation of the £100 penalty
HMRC may still reject this at first instance. That is normal. Marcus should escalate to a review and, if necessary, the First-tier Tribunal, where a documented bereavement claim of this kind has a strong track record.
The same framework applies whether Marcus misses an annual Self Assessment deadline or an MTD quarterly update. The law is the same; only the penalty structure differs.
Don't Confuse Reasonable Excuse With Special Circumstances
There is a separate provision worth knowing: HMRC has discretion to reduce or waive penalties where there are "special circumstances" that make the full penalty disproportionate, even where no reasonable excuse exists. This is narrower and harder to invoke, but it exists under paragraph 16 of Schedule 55 Finance Act 2009.
If your situation does not meet the reasonable excuse test, a special circumstances argument may still reduce your exposure. HMRC is reluctant to use this provision generously, but a well-argued case at tribunal can compel them.
For the related question of late payment interest rather than filing penalties, HMRC Interest on Late Tax Payment: The Silent Penalty explains how that separate charge accumulates and what, if anything, can be done about it.
People also ask
The Takeaway: Most People Give Up Too Early
Remember that 600,000-plus penalty notices from 2022/23? A significant proportion of those recipients had circumstances that would qualify as a reasonable excuse under UK tax law. Most accepted the fine, paid it, and moved on.
The reasonable excuse process is not designed to be obvious. HMRC benefits financially when taxpayers do not appeal. A £100 fine paid without challenge costs HMRC nothing. A well-documented appeal that reaches tribunal costs them time and resource.
If you received a penalty and believe you had a genuine reason for missing the deadline, write the appeal letter. Cite section 118(2) TMA 1970. Document your timeline. Submit your evidence. Expect a first rejection and escalate anyway. The law is on your side if the facts are.
And if you want to avoid the situation entirely, the single most effective thing a sole trader can do is make quarterly filing habitual before MTD makes it mandatory. Start with a tool that removes the friction, so that illness, bereavement, or a chaotic December never puts you in the position of needing to explain yourself to HMRC in the first place.
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