The short version: A reasonable excuse is a valid reason HMRC will accept for missing a tax deadline. If you have one, you can appeal against penalties. But HMRC sets a high bar.
What counts as reasonable?
Serious illness or hospitalisation around the deadline. Bereavement of a close family member. HMRC’s systems being down. Postal delays or disasters like fires and floods. Basically, circumstances genuinely beyond your control.
What doesn’t count?
“I forgot” doesn’t work. Neither does “I didn’t know” or “I was too busy.” Relying on someone else who let you down usually isn’t enough either, unless they were a professional you reasonably trusted.
How do you appeal?
Write to HMRC explaining what happened, when, and why it prevented you from meeting the deadline. Provide evidence if you can. You still need to file your return and pay what you owe as soon as possible.
Does it always work?
No. HMRC reviews each case individually. Having a reasonable excuse doesn’t guarantee your penalty will be cancelled, but it’s worth appealing if you genuinely had one.
Facing penalties and think you have a reasonable excuse? Let us help you put together your appeal.
