What counts as a 'reasonable excuse' to HMRC? The complete list
A reasonable excuse is something unexpected or outside your control that stopped you meeting a tax obligation. HMRC's accepted examples include the death of a partner or close relative shortly before a deadline, unexpected hospital stays, serious or mental illness, computer failures while filing, HMRC's own online service problems, fire, flood, theft, and postal delays. Two rules decide most appeals: the excuse must cover the period of default, and you must have put things right as soon as you reasonably could once it ended.
Written by the team behind Agent Arthur, our HMRC and tax specialist. This guide is general information about UK law, reviewed for accuracy.What HMRC accepts (its own published list)
- The death of a partner or close relative shortly before the deadline
- An unexpected stay in hospital that prevented you dealing with your tax affairs
- A serious or life-threatening illness
- Computer or software failure just before or while preparing your online return
- Problems with HMRC's online services
- Fire, flood or theft that prevented filing
- Postal delays you couldn't have predicted
- Delays related to a disability, or a mental-health condition that affected you at the time
What HMRC (almost) always rejects
- You relied on someone else, such as an accountant or a partner, and they let you down (unless you can show you took reasonable care yourself)
- Your cheque bounced or the payment failed with funds available
- You found the online system too difficult
- You didn't get a reminder from HMRC
- You made a mistake on the return itself (that's a different penalty regime: accuracy, not lateness)
The two rules that decide appeals
First, the excuse must actually cover the default. A crisis in March doesn't explain missing a January deadline; a January crisis doesn't by itself explain filing in June. Map your timeline against the deadline and the eventual filing date.
Second, and this is the one that catches people out, you must have sorted things out 'as soon as you reasonably could' after the excuse ended. If you recovered in February and filed in July, expect HMRC to ask about those five months. A strong appeal answers that question before it's asked.
Evidencing it
HMRC decides on paper, so paper wins: death certificates, hospital discharge letters, GP letters, screenshots of HMRC service outages, software error messages, crime reference numbers. One piece of independent evidence per claim is the standard to aim for. Keep the tone factual: the officer reading it processes hundreds of these, so make theirs an easy yes.
Turn your circumstances into HMRC's own languageArthur drafts your appeal mapped to HMRC's reasonable-excuse criteria: the timeline, the two rules answered, and the evidence checklist, ready to send.£5 launch price (normally from £19.99)Start my appeal letterCommon questions
Is mental health accepted as a reasonable excuse?
Yes. HMRC's guidance explicitly includes mental-health conditions that affected you at the relevant time. A short GP or specialist letter confirming the period helps considerably, and appeals on this ground succeed regularly.
My accountant missed the deadline: is that my problem?
HMRC's starting position is that relying on someone else isn't an excuse, unless you took reasonable care: you instructed them in good time, provided everything they needed, and chased. Evidence that, and the argument becomes live.
Does 'I couldn't afford to pay' count?
Not for filing, because you can file a return without paying. For late payment, insufficiency of funds generally isn't an excuse unless caused by events outside your control (e.g. a major customer's insolvency). There's a separate route, Time to Pay, for genuine affordability problems.
How long do I have to appeal?
30 days from the date on the penalty notice, for each penalty. Late appeals are accepted with a good reason for the lateness of the appeal itself, so explain both.
What if HMRC rejects my reasonable excuse?
You can request a statutory review by an officer not previously involved. It's free, and a meaningful number of penalties are overturned there. After that, the First-tier Tax Tribunal, also free to lodge. Rejection of the first letter is not the end.