HMRC Penalty Appeal Letter Template & Generator

If you need to appeal against HMRC penalty citing reasonable excuse, a written letter is the recommended first step — it creates a clear record and shows you're pursuing the matter formally. Below is what a strong hmrc penalty appeal letter should include, plus a free tool to generate yours.

What this letter needs to cover

• State the penalty reference, date and amount
• Set out the reasonable excuse clearly (illness, bereavement, postal failure, HMRC system error — specify from situation)
• Reference HMRC's reasonable excuse guidance
• Request the penalty is cancelled
• Note right to tribunal appeal if the appeal is rejected

What counts as a "reasonable excuse" to HMRC

HMRC can waive a penalty if you had a genuine reasonable excuse for missing a deadline — this generally means something unexpected and outside your control, like a serious illness, bereavement, or a genuine systems failure, rather than simply forgetting or being busy. Being specific and honest about your circumstances, with evidence where possible, gives an appeal the best chance of success.

What to include before you send it

• The specific penalty and deadline you're appealing against
• A clear, honest explanation of what happened and why it prevented you from meeting the deadline
• Any supporting evidence — medical certificates, documentation of the specific issue
• Confirmation of the date you took action once the reasonable excuse ended

Acting promptly once the excuse ends matters

HMRC generally expects you to put things right as soon as reasonably possible once your reasonable excuse ends — continuing to delay significantly after the original issue has resolved can undermine an otherwise valid excuse.

Frequently Asked Questions

Does "I forgot" or "I was too busy" count as a reasonable excuse?
No — HMRC's guidance is clear that these don't meet the reasonable excuse test, since a genuine reasonable excuse needs to be something unexpected and outside your normal control.

What if my appeal is rejected?
You can request a formal review by a different HMRC officer, and if still unsuccessful, appeal to the independent tax tribunal.

See our full letter template & generator library for related letters, or use our free checkers for guidance specific to your situation.