HMRC Penalty Appeal Letter Template — Free Guide

Writing an appeal letter to HMRC can feel daunting, especially if you have never dealt with a tax penalty before. But the structure of a successful appeal is surprisingly consistent. This guide breaks down exactly what your letter should contain, which legislation to reference, and the common mistakes that get appeals rejected.

Why a written appeal is stronger than a phone call

While HMRC allows you to appeal by phone, a written appeal is almost always more effective. A letter creates a permanent record, allows you to cite specific legislation, and gives the HMRC officer a clear, structured case to assess. Phone appeals rely on the officer's notes, which may not capture all the details of your argument.

A well-written appeal letter also demonstrates that you take the matter seriously. HMRC officers review hundreds of appeals — a professional, clearly structured letter stands out from vague complaints.

The structure of a winning appeal letter

Every successful HMRC penalty appeal letter follows a similar structure. Here is the template framework that chartered tax advisers use:

1. Header and reference details

Start your letter with:

• Your full name and address
• Your Unique Taxpayer Reference (UTR)
• Your National Insurance number
• The penalty reference number (from your penalty notice)
• The tax year the penalty relates to
• The date of the penalty notice

This allows HMRC to immediately locate your case and match your appeal to the correct penalty.

2. Opening statement

State clearly that you are writing to appeal the penalty, and identify the specific penalty type. For example: “I am writing to appeal the late filing penalty of £100 issued on [date] for the [tax year] Self Assessment tax return, penalty reference [reference number].”

3. Your reasonable excuse

This is the core of your appeal. Describe what happened, with specific dates and details. Follow the structure established in Perrin v HMRC [2018] UKUT 156:

• What happened: Describe the event or circumstance that prevented you from filing
• When it started: Give the date the obstacle arose
• When it ended: State when you were able to resume normal activities
• What you did afterwards: Show that you filed your return without unreasonable delay once the obstacle was removed

4. Legal references

Citing the correct legislation shows HMRC that your appeal is informed and serious. For a late filing penalty, reference:

• Finance Act 2009, Schedule 55, paragraph 23 — provides the statutory basis for the reasonable excuse defence
• Taxes Management Act 1970, s.93 — the original late filing penalty provision
• Perrin v HMRC [2018] UKUT 156 — the leading case on the structured test for reasonable excuse

For late payment penalties, cite Schedule 56 instead of Schedule 55. For VAT penalties, cite the VAT Act 1994 and relevant default surcharge provisions.

5. Evidence

List any evidence you are enclosing. Common supporting documents include:

• GP or hospital letters confirming illness or treatment
• Death certificates or funeral director correspondence
• Screenshots of HMRC website errors or outage reports
• Insurance claims or emergency service reports (fire/flood)
• Correspondence with your accountant showing reliance

6. Closing request

End your letter with a clear request: “I respectfully request that HMRC cancels the penalty of £[amount] in light of the reasonable excuse outlined above and the supporting evidence enclosed.”

Common mistakes that get appeals rejected

• Being too vague: “I was ill” is not enough. Specify the condition, dates, and how it prevented you from filing.
• Not addressing the delay: Even if you had a genuine excuse, you must explain why you filed when you did, not just why you missed the original deadline.
• Using an invalid excuse: Forgetting, being busy, or not knowing about the deadline will always be rejected.
• Missing the 30-day window: Appeal within 30 days of the penalty notice date. Late appeals require additional justification.
• Being emotional instead of factual: HMRC officers assess appeals against legal criteria. A calm, evidence-based letter is far more effective than an angry complaint.
• Not citing legislation: A letter that references the Finance Act and Perrin v HMRC is taken more seriously than one that does not.

Where to send your appeal

You can submit your appeal letter in several ways:

• By post: Send to the address printed on your penalty notice. Keep a copy and consider using recorded delivery.
• Online:Log in to Government Gateway and use the “Appeal a penalty” option. You can paste your letter text into the online form.
• Via form SA370: Download the official appeal form from GOV.UK and use your letter as supporting information.

If your appeal is rejected

A rejected appeal is not the end. You have two further options:

• Statutory review: Request that a different, independent HMRC officer reviews your case. This is free and often produces a different outcome.
• First-tier Tribunal (Tax Chamber): Appeal to an independent tribunal that is completely separate from HMRC. The tribunal is free to use and has the power to cancel penalties that HMRC has refused to cancel.