How to appeal an HMRC penalty: the 30-day process, step by step

You have 30 days

You must appeal within 30 days of the date on the penalty notice. Miss it and HMRC can refuse to consider the appeal unless you have a reasonable excuse for the late appeal too.

How to appeal

• Online: through your HMRC online account or the Self Assessment appeal service - fastest.
• By post: form SA370 for Self Assessment penalties, or a letter quoting the penalty reference and your Unique Taxpayer Reference (UTR).

What to include

• The penalty reference and your UTR.
• The reasonable excuse - what happened, the dates, and why it stopped you meeting the deadline.
• That you put things right as soon as the excuse ended (filed or paid promptly).
• Any evidence - a GP letter, a death certificate, correspondence showing an IT failure.

If HMRC rejects it

You can ask for a review by a different HMRC officer, and if still refused, appeal to the independent First-tier Tribunal (Tax). Many penalties are cancelled at review before ever reaching a tribunal.