Appealing Self-Assessment Tax Penalties: A Practical Guide

Last updated: March 2026

Quick Answer

If HMRC has imposed a penalty for late filing or late payment of your self-assessment tax return, you can appeal. The penalty structure is fixed: £100 for filing up to 3 months late, with escalating daily and percentage-based penalties after that. Your main defence is "reasonable excuse" — a genuine reason beyond your control that prevented you from meeting the deadline. You can appeal to HMRC directly, request a review, or take your case to the First-tier Tribunal (Tax Chamber). This guide explains the penalty structure, what counts as a reasonable excuse, and how to prepare your appeal.

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How Self-Assessment Penalties Work

Self-assessment is the system by which individuals report their income and capital gains to HMRC and pay the tax due. If you are within the self-assessment system — whether as a sole trader, landlord, company director, or higher-rate taxpayer — you are legally required to file a return by the deadline and pay the tax on time.

When you miss these deadlines, HMRC imposes automatic penalties. Understanding the penalty structure is the first step to deciding whether to appeal.

Late Filing Penalties

The penalties for filing a self-assessment tax return late are set out in Schedule 55 of the Finance Act 2009:

This means that a return filed 12 months late could attract penalties of up to £1,600 plus 10% of the tax due — even before any interest is added.

Late Payment Penalties

Separate penalties apply for paying your tax late. These are set out in Schedule 56 of the Finance Act 2009:

These penalties are cumulative. A taxpayer who pays 12 months late faces total penalties of 15% of the tax outstanding, plus statutory interest.

Interest

On top of penalties, HMRC charges interest on overdue tax from the due date until the date of payment. The interest rate changes periodically but has been significantly higher since the Bank of England base rate increases of 2022-2024. As at March 2026, the late payment interest rate is 7.25% per annum (check HMRC's website for the current rate, as this changes with the base rate).

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The Reasonable Excuse Defence

The most important defence to a self-assessment penalty is "reasonable excuse." If you can show that you had a reasonable excuse for the late filing or late payment, the penalty must be cancelled.

What the Law Says

Paragraph 23 of Schedule 55 FA 2009 (for late filing) and paragraph 16 of Schedule 56 FA 2009 (for late payment) provide that a penalty does not arise if the taxpayer satisfies HMRC — or, on appeal, the tribunal — that there was a reasonable excuse for the failure.

The legislation adds two important conditions:

1. The excuse must persist — if the excuse ceases, you must comply without unreasonable delay
2. Reliance on a third party is not automatically reasonable — nor is insufficiency of funds, unless attributable to events beyond your control

What Counts as a Reasonable Excuse?

The tribunal takes a practical approach. The question is: would a reasonable taxpayer, in the same circumstances, have been unable to meet the deadline? There is no exhaustive list, but the following have been accepted by tribunals:

Building Your Reasonable Excuse Case

To succeed with a reasonable excuse defence, you need evidence. The tribunal will want to see:

1. What happened — a clear factual account of the circumstances
2. When it happened — the timing relative to the filing or payment deadline
3. How it prevented compliance — the causal link between the excuse and the failure
4. What you did when the excuse ended — evidence that you filed or paid without unreasonable delay once the excuse ceased
5. Supporting documents — medical certificates, hospital records, death certificates, HMRC correspondence, screenshots of IT failures, or other contemporaneous evidence

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How to Appeal a Self-Assessment Penalty

You have three options for challenging a penalty, and it is important to understand them in order.

Option 1: Appeal Directly to HMRC

You can write to HMRC (or use the online service) to appeal the penalty. Your appeal should:

• Quote your Unique Taxpayer Reference (UTR) and the penalty reference number
• State clearly that you are appealing the penalty
• Set out your reasonable excuse in detail
• Attach supporting evidence
• Confirm the date on which the excuse ended and the date you filed or paid

HMRC will consider your appeal and either cancel the penalty, reduce it, or uphold it.

Option 2: Request an Internal Review

If HMRC rejects your initial appeal, you can ask for an internal review. A different HMRC officer — one who was not involved in the original decision — will re-examine the case. HMRC aims to complete reviews within 45 days.

The review is free and often worthwhile. Review officers sometimes take a more balanced view than the original decision-maker.

Option 3: Appeal to the First-tier Tribunal

If the internal review upholds the penalty (or if you prefer to bypass the review entirely), you can appeal to the First-tier Tribunal (Tax Chamber). There is no filing fee.

The tribunal is independent of HMRC and will look at your case afresh. You can choose whether to have the appeal decided on the papers or at an oral hearing. For reasonable excuse appeals, an oral hearing is usually preferable — it gives you the opportunity to explain the circumstances in your own words and answer the judge's questions.

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Preparing Your Appeal Bundle for the Tribunal

If your appeal reaches the tribunal, you will need to prepare a bundle containing all the documents relevant to the dispute.

What to Include

Organising Your Bundle

The tribunal expects a paginated, indexed bundle. Number every page consecutively from page 1, and include an index at the front listing each document with its page reference. For electronic bundles, include bookmarks and ensure the PDF is text-searchable.

A well-organised bundle demonstrates to the tribunal that you are taking the process seriously. It also makes the hearing run more smoothly, because the judge can find documents quickly when you refer to them.

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What Happens at the Tribunal Hearing

Self-assessment penalty appeals are usually classified as "default paper" cases, meaning the tribunal will decide them on the papers unless you request an oral hearing. Always request an oral hearing if your case depends on explaining your personal circumstances — a letter cannot convey the same impact as a person explaining what happened to them.

The Hearing Process

1. The judge confirms the issues — typically, whether you had a reasonable excuse and whether you remedied the failure without unreasonable delay
2. HMRC presents its case — often briefly, relying on the statement of case already filed
3. You present your case — this is your opportunity to explain what happened, referring to your bundle
4. Questions from the judge — the judge may ask for clarification on specific points
5. Decision — the judge may give a decision immediately or reserve it

Tips for the Hearing

• Prepare thoroughly — know your bundle inside out
• Be honest — if part of the delay was your own oversight, say so, but explain the circumstances
• Focus on the excuse, not the unfairness — "the penalty is too harsh" is not a legal argument; "I had a reasonable excuse" is
• Bring spare copies — ensure the tribunal and HMRC each have a copy of your bundle
• Stay calm — the tribunal is used to hearing from unrepresented taxpayers and will be patient

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Common Pitfalls to Avoid

1. "I Didn't Know I Had to File"

Ignorance of the law is not a reasonable excuse. If HMRC issued you with a notice to file (form SA316), you are legally obliged to file a return, whether or not you have tax to pay.

2. "My Accountant Was Supposed to Do It"

Reliance on a third party is specifically excluded from the reasonable excuse defence by the legislation — unless you can show that you took reasonable care to ensure the third party was reliable and that their failure was unexpected.

3. "I Couldn't Afford to Pay"

Insufficiency of funds is not a reasonable excuse for late payment — unless the shortfall was caused by something beyond your control, such as a client going bankrupt and failing to pay a large invoice.

4. Waiting Too Long to Appeal

You have 30 days from the date of the penalty notice to appeal. If you miss this deadline, you can still apply for late permission, but the longer the delay, the harder it becomes to justify.

5. Not Filing Even After the Penalty

If you still have not filed the return, file it now. Even if you are appealing the penalty, continuing not to file attracts further penalties and undermines your credibility.

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Using BundleCreator for Penalty Appeals

Putting together a penalty appeal bundle — organising medical evidence, HMRC letters, and your timeline into a paginated, indexed document — is a task that BundleCreator makes straightforward.

With BundleCreator, you can:

• Upload all your evidence, correspondence, and tax documents
• Arrange them in a logical order with simple drag-and-drop
• Apply automatic consecutive pagination
• Generate a hyperlinked index and PDF bookmarks
• Ensure your bundle is text-searchable and professionally formatted
• Export a tribunal-ready bundle in minutes

A professional bundle shows the tribunal you have taken your appeal seriously — and BundleCreator handles the formatting so you can focus on your case.

Start preparing your penalty appeal bundle →

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Frequently Asked Questions

Can I appeal a self-assessment penalty if I had no tax to pay?

Yes. The initial £100 late filing penalty applies whether or not you owe any tax. You can still appeal on the basis of reasonable excuse — the absence of tax due does not affect the penalty itself, but it may be a factor in your argument that the penalty is disproportionate.

How long does HMRC take to respond to a penalty appeal?

HMRC aims to respond to penalty appeals within 40 working days, though it can take longer during busy periods. If you do not receive a response, you can escalate the matter by requesting a review or appealing to the tribunal.

Is there a fee to appeal to the tax tribunal?

No. There is no filing fee for appeals to the First-tier Tribunal (Tax Chamber). This applies to self-assessment penalty appeals and all other tax appeals.

What if I have multiple penalties for the same tax year?

You can appeal multiple penalties in a single notice of appeal. If the same reasonable excuse applies to all the penalties (for example, you were hospitalised during the entire period), you should explain this once and make clear that it covers all the penalties.

Can HMRC waive a penalty without me appealing?

HMRC has the power to reduce or cancel penalties in certain circumstances — for example, under its collection and management powers or where special circumstances exist. However, this is rare, and you should not rely on HMRC's discretion. If you believe the penalty is wrong, appeal formally.

What if my accountant admits it was their fault?

If your accountant accepts that the failure was their professional error, obtain a written admission from them. While reliance on a third party is not automatically a reasonable excuse, evidence that you took reasonable steps to help you work within the rules — and that the accountant's failure was genuinely unexpected — can support your appeal.

Can penalties be suspended?

Late filing and late payment penalties under Schedules 55 and 56 FA 2009 cannot be suspended. However, inaccuracy penalties under Schedule 24 FA 2007 can be suspended if HMRC agrees conditions — for example, improving your record-keeping. This distinction matters if you are facing multiple types of penalty.

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This article is provided for general informational purposes only and does not constitute legal or tax advice. The law and procedure described applies to England and Wales. If you are unsure about your specific situation, seek independent legal or professional advice.