Almost every HMRC penalty regime contains a statutory escape valve known as "reasonable excuse". If you can show that an event outside your normal control caused the failure to file or pay on time, the penalty must be discharged. The catch is that HMRC and the tribunals apply this concept narrowly, and the categories that succeed in practice are tighter than most taxpayers expect.
The legal test
"Reasonable excuse" is not defined exhaustively in legislation. The courts have settled on a test that asks: would a reasonable, prudent taxpayer with similar circumstances and obligations have acted differently? The excuse must explain the failure, must have existed throughout the period of default, and the taxpayer must have remedied the failure as soon as the excuse ended.
Categories HMRC routinely accepts
The following types of circumstance, when properly documented, frequently succeed:
- Serious illness or hospitalisation of the taxpayer or someone they cared for, supported by medical evidence covering the relevant period.
- Bereavement close to the deadline, particularly of immediate family.
- Fire, flood or theft that destroyed records or premises, with insurance correspondence or police references.
- HMRC's own system outages, where the published outage covered the filing or payment window. HMRC maintains a public service status page and references its own outages in tribunal decisions.
- Postal or courier failure for paper filings, where there is proof of timely dispatch (recorded delivery receipt with a date pre-deadline).
- Bereavement of a key adviser (e.g. accountant) close to the deadline, particularly where records were in the adviser's possession.
Categories HMRC routinely rejects
Equally instructive are the excuses that almost never succeed:
- "I forgot" or "I was too busy". Pressure of other work is not a reasonable excuse for a missed statutory deadline.
- "I relied on my accountant". This is the most common ground of appeal and one of the most common to fail. Taxpayers remain personally responsible for compliance; the remedy for an accountant's failure is against the accountant, not against HMRC. There are narrow exceptions where the adviser's failure was wholly outside the taxpayer's control and the taxpayer had taken reasonable steps to check.
- "I did not have the funds" for late payment penalties. Insufficiency of funds is excluded by statute from being a reasonable excuse, except where the shortage was itself caused by an unforeseeable event.
- "I did not understand the rule". Ignorance of the law is not a reasonable excuse. There is a narrow exception where the rule was genuinely obscure or had been recently changed without adequate publicity.
- IT failures that were foreseeable — a computer crash on the morning of 31 January after months of warning, or a card declining at 11:55pm on the deadline.
The "ceased to apply" rule
Even when an excuse exists, you must act promptly once the cause has ended. A hospitalisation in October does not excuse a Self Assessment filing still outstanding in March. The tribunal will ask: when did the excuse end, and did you act without unreasonable delay thereafter? Two to three weeks is usually treated as reasonable; six months almost never is.
How to document an excuse
- Create contemporaneous evidence. Diary entries, photographs, hospital admission documents, emails to family explaining the situation — anything dated at the time has far more weight than a reconstruction.
- Map the timeline. When did the event start, when did it end, what did you do in the days that followed?
- Quantify the impact. Why did this particular event prevent you from filing/paying? "I was unwell" is weaker than "I was on intravenous antibiotics and unable to operate a computer for three weeks".
- Demonstrate normality otherwise. A clean prior compliance record strengthens any excuse; a history of repeated late filings undermines it.
Appeals: where many succeed
Many reasonable excuse appeals succeed when the taxpayer has clear, contemporaneous documentation and a coherent timeline. The First-Tier Tax Tribunal is the destination if HMRC's review upholds the penalty, and the tribunal is often more sympathetic than the original case officer, particularly for first-time appellants. Our business advisory team has supported directors through the full process and the message we consistently give is: do not appeal on emotion, appeal on evidence.
If you have received a penalty and believe a reasonable excuse applies, book a call for a confidential review before the 30-day appeal window closes, or reach us via the contact page. We are also happy to support clients who have engaged us for ongoing tax planning with the procedural side of any historical penalty issues.