Read the penalty notice and its appeal instructions promptly. Appeals are normally due within 30 days. Explain what prevented you meeting the deadline, give relevant dated evidence and say what you did once the problem ended. Appealing does not file a missing return or pay the tax.
Read the notice before drafting the appeal
Identify the tax year, type of penalty, issue date and reason. Check the appeal instructions and normal 30-day window. If the return was not required, asking HMRC to withdraw the filing requirement can be a different route from arguing a reasonable excuse.
Explain what happened and when
A useful explanation connects the event to the missed deadline. Set out the dates, why it prevented compliance, when it ended and what you did afterwards. Serious illness, bereavement or a service failure needs the relevant facts; the label alone does not establish the outcome.
A short structure is: “The deadline was [date]. [Event] prevented filing from [date] to [date]. I filed on [date] after it ended. I enclose [relevant evidence].” Use only true facts. An example structure is not a promise that the excuse qualifies.
Keep the evidence relevant
Include the notice, dated correspondence and evidence that supports the actual period. Avoid unnecessary medical or other private details. A general outage screenshot from weeks later may not explain a failed attempt at the deadline.
Deal with the missing return or tax too
An appeal does not submit the return, settle tax or automatically stop every charge. If the appeal is late, explain that delay separately. Ask TaxSimba to confirm whether appeal support is available within the engagement or needs separate work; cancellation cannot be promised in advance.
Use HMRC’s appeal route for the actual penalty
HMRC’s Self Assessment appeal checker directs you to the applicable online route or forms SA370 and SA371. Follow the notice and keep proof of sending the appeal.
Record the penalty issue date immediately. HMRC normally allows 30 days from issue to contact it or appeal; explain any late appeal separately. Track the appeal, the return and the unpaid tax as separate tasks so sending a letter does not leave the original problem unresolved.
Show how the event affected the deadline
Illustrative example.
For a fictional unexpected hospital admission, a useful timeline would record the obligation’s deadline, the admission and discharge dates, why the illness prevented compliance, and when filing resumed. A letter showing an admission months away from the deadline would need further explanation.
Use only genuine evidence and relevant facts. The example illustrates how to organise an appeal, not a prediction that HMRC will accept it. If the appeal itself is late, explain that delay separately from the original missed obligation.
| Check | Practical action |
|---|---|
| Obligation | Identify the return or payment and actual deadline. |
| Preventing event | Explain the dated facts and connection to non-compliance. |
| Recovery action | Record what happened when the obstacle ended. |
Is saying “personal difficulties” enough?
Explain the actual event, dates and effect on the obligation. A label alone does not establish the grounds.
Does an appeal mean I can ignore the notice?
No. Read the notice and check payment, interest and the underlying filing position while the appeal is considered.
Download a checklist for this guide
- Penalty notice, issue date and tax year
- Appeal deadline
- Dated factual timeline
- Relevant genuine evidence
- Filing, payment and appeal status