How to Appeal an HMRC Penalty in 2026: Step-by-Step Guide
A plain-English 2026 guide to appealing HMRC penalties: deadlines, reasonable excuse, the SA370 and online routes, tribunals, and what to do first.
Quick answer
To appeal an HMRC penalty, act within 30 days of the notice. State your penalty reference and explain either that you have a reasonable excuse or that the penalty is wrong. For Self Assessment late filing, file the return, then appeal online or by form SA370. If refused, ask for a statutory review and then the tribunal.
What kind of penalty are you facing?
HMRC issues penalties for several different things, and the appeal route is broadly the same but the detail differs. The most common penalties are:
- Late filing of a Self Assessment tax return.
- Late payment of tax you owe.
- Errors or inaccuracies on a return (which can be "careless" or "deliberate").
- Failure to notify HMRC that you needed to register, for example for Self Assessment or VAT.
The first job is to read the notice carefully. It tells you the penalty type, the amount, the period it relates to, the legal reason, and crucially the date - which starts your 30-day clock. Keep the notice and the envelope or a screenshot of the digital version.
The 30-day deadline
You normally have 30 days from the date on the penalty notice to appeal. Inside that window the process is straightforward. Outside it, you must ask HMRC to accept a late appeal and give a good reason for the delay - a serious illness or a notice that never reached you, for example. HMRC and the tribunal both look closely at how promptly you acted, so do not let a late appeal drift.
If you are still within time, you can usually appeal online through your HMRC account or Government Gateway, or in writing. For Self Assessment late filing penalties, you generally must have filed the outstanding return before HMRC will cancel the penalty for not filing it.
Grounds for appeal
There are really two distinct arguments, and it helps to be clear which one you are making.
Reasonable excuse
A reasonable excuse is something unexpected or outside your control that stopped you meeting the obligation. Examples HMRC commonly accepts include:
- A serious or life-threatening illness, or that of a close family member.
- A bereavement close to the deadline.
- A fire, flood, or theft that destroyed your records.
- A failure of HMRC's own online service.
- Postal delays you could not have predicted.
To succeed, the excuse must cover the whole period of the delay, and you must have put things right as soon as the excuse ended. Reasons HMRC rarely accepts on their own include not having the money to pay, finding the return too difficult, or simply forgetting. "I relied on my accountant" is also weak unless you can show you did everything reasonable to make sure the work was done.
The penalty is wrong
This is a different argument: you are saying the penalty should never have been issued. Perhaps you did file on time and have the receipt, you were not required to file at all, or HMRC's figures are mistaken. Here you provide proof - a filing confirmation, correspondence, or evidence of your circumstances - and ask HMRC to cancel the penalty outright.
How to appeal, step by step
- Read the notice and note the penalty reference and the date.
- Decide your grounds: reasonable excuse or wrong penalty.
- Put right whatever caused the penalty - for late filing, submit the outstanding return.
- Gather evidence: medical letters, death certificates, insurance or repair documents, screenshots of HMRC outages.
- Appeal within 30 days, online via your HMRC account or on paper with form SA370 for Self Assessment.
- Keep copies of everything you send, with dates.
- Wait for HMRC's decision; if rejected, consider a statutory review, then the tribunal.
The table below summarises the main routes.
| Stage | What it is | Typical time limit | Cost |
|---|---|---|---|
| First appeal | Ask HMRC to cancel or reduce the penalty | 30 days from notice | Free |
| Statutory review | Fresh look by an uninvolved HMRC officer | 30 days from rejection | Free |
| First-tier Tribunal | Independent judge hears the case | 30 days from review or decision | Free to use |
What to put in the appeal
Whether you appeal online or on form SA370, be clear and factual. Include:
- The penalty reference and the tax year or period.
- Your name, Unique Taxpayer Reference, or other HMRC reference.
- A short, dated account of what happened and why.
- A statement of your grounds (reasonable excuse, or that the penalty is wrong).
- Copies of supporting evidence.
Stick to the facts and the timeline. You do not need legal language; you need to show that, on the facts, you had a reasonable excuse or that the charge is mistaken.
Pay the tax, dispute the penalty
Appealing a penalty does not stop interest running on any unpaid tax. The penalty itself is usually paused while the appeal is considered, but interest on the underlying tax keeps building. For that reason it is often sensible to pay the tax, or set up a Time to Pay arrangement with HMRC, even while you dispute the fine. If your appeal succeeds the penalty is cancelled; the tax and its interest stand unless those too are wrong.
If you are unsure how much tax you actually owe - for example because your Self Assessment figures are estimates - work it out before you decide what to pay. Our
Self-Employed Tax Calculator
Calculate income tax, Class 2 and Class 4 National Insurance for self-employed and sole traders for 2025/26.
Open Self-Employed Tax calculatorIncome Tax Calculator
Work out how much income tax you owe using the latest 2025/26 UK tax bands.
Open Income Tax calculatorIf HMRC says no: review and tribunal
If HMRC rejects your appeal, they must offer you a statutory review. This is a free second look by an officer who had nothing to do with the original decision. You normally have 30 days to accept the offer. The reviewer can agree with you, partly agree, or uphold the penalty.
If you still disagree after the review - or you would rather skip it - you can take the case to the First-tier Tribunal (Tax Chamber). The tribunal is independent of HMRC, free to use, and many appellants represent themselves. You normally have 30 days from the review conclusion, or from HMRC's decision if you did not have a review, to lodge the appeal. The judge decides on the evidence whether the penalty was correctly charged and whether you had a reasonable excuse.
A quick comparison of your options
Handling it yourself works well for a clear-cut Self Assessment late filing penalty with strong evidence of a reasonable excuse - the online service and form SA370 are designed for exactly this. Bringing in a tax adviser makes more sense for large penalties, inaccuracy or "deliberate" penalties, complex VAT or company cases, or a tribunal hearing where the amount at stake justifies the fee.
Before paying for help, weigh the likely fee against the penalty. A small fixed late filing penalty rarely warrants professional fees; a five-figure inaccuracy penalty often does.
Avoiding the next penalty
The cheapest penalty is the one you never get. A few habits make a real difference:
- Note all HMRC deadlines and file or pay early, not on the day.
- Keep your contact and address details up to date so notices reach you.
- Keep records and filing receipts so you can prove what you did.
- If you cannot pay, contact HMRC about a Time to Pay arrangement before the deadline rather than after.
- Check your figures before you file - errors invite inaccuracy penalties.
For Self Assessment in particular, knowing your likely bill in advance removes the cash-flow surprise that leads to late payment. Run your numbers with the
Self-Employed Tax Calculator
Calculate income tax, Class 2 and Class 4 National Insurance for self-employed and sole traders for 2025/26.
Open Self-Employed Tax calculatorThe bottom line
Most HMRC penalties can be appealed, and many late filing penalties are cancelled when there is a genuine reasonable excuse backed by evidence. Move fast - the 30-day window matters - put right whatever triggered the penalty, set out your grounds clearly, and escalate to a free statutory review and then the tribunal if HMRC refuses. Because there is no extra charge for appealing and losing, a well-founded appeal is almost always worth making.
For the precise current penalty amounts, daily rates, and the exact online appeal steps, check the relevant guidance on gov.uk, as these figures can change between tax years.
Frequently asked questions
How long do I have to appeal an HMRC penalty?
You normally have 30 days from the date on the penalty notice to appeal. If you miss that deadline you can still ask HMRC to accept a late appeal, but you must explain why it is late and show a good reason for the delay. The sooner you act the better, because HMRC and the tax tribunal both weigh how long you took to respond. Keep the envelope or the digital notice so you can prove the date.
What counts as a reasonable excuse?
A reasonable excuse is something unexpected or outside your control that stopped you meeting an obligation - for example a serious illness, a bereavement, a fire or flood, or an HMRC service failure. It must explain the whole period of delay, and you must have put things right as soon as the excuse ended. Not having the money to pay, finding the tax too difficult, or relying on someone else are not normally accepted on their own.
Can I appeal a penalty if I have not paid the tax yet?
Yes. You can appeal a penalty separately from paying the underlying tax. However, interest keeps running on any unpaid tax while the appeal is considered, so it is often sensible to pay the tax (or set up a payment plan) even while you dispute the penalty. If your appeal succeeds the penalty is cancelled, but the tax and any interest on it still stand unless those are also wrong.
Does appealing pause the penalty?
Submitting an appeal generally pauses HMRC's collection of that penalty until the appeal is decided. It does not pause interest on unpaid tax. If HMRC rejects your appeal you can ask for a statutory review or take the case to the First-tier Tribunal. You can also ask HMRC to postpone payment of the disputed amount while the matter is resolved.
What is a statutory review?
A statutory review is a free second look at HMRC's decision by an officer not involved in the original case. After HMRC rejects your appeal they must offer you a review. You usually have 30 days to accept. The reviewer can agree with you, partly agree, or uphold the penalty. If you still disagree after the review you can take the case to the tax tribunal, normally within 30 days of the review conclusion.
How do I appeal a Self Assessment late filing penalty?
If you have a reasonable excuse you can often appeal online through your HMRC account once the original return is filed, or by completing form SA370 and posting it. State the penalty reference, the reason for the delay, and the dates involved. Attach evidence where you can. You must normally have filed the outstanding return before HMRC will consider cancelling the penalty for not filing it.
Will I be charged more for appealing and losing?
No. There is no extra penalty simply for making an appeal that does not succeed. The original penalty stands, and interest continues on any unpaid tax, but HMRC does not add a charge for trying. The tax tribunal is also free to use, although you may have your own costs if you pay for professional help. This means there is little downside to a well-founded appeal.
Can HMRC charge daily penalties on top of the first fine?
For Self Assessment, a fixed penalty can apply once a return is late, with further daily and tax-geared penalties building up the longer it stays outstanding. The exact amounts depend on the penalty type and how late the return is, so check your notice and gov.uk for the current figures. The key point is that delay makes penalties worse - file the return and appeal quickly rather than waiting.
Do I need an accountant to appeal?
No. Many appeals, especially Self Assessment late filing penalties with a clear reasonable excuse, can be handled yourself using the online service or form SA370. An accountant or tax adviser can help with complex cases, large amounts, or tribunal hearings, and an authorised agent can appeal on your behalf. Weigh the likely fee against the penalty at stake before paying for help.
What if I think the penalty is simply wrong?
If the penalty was raised in error - for example you did file on time, you were not required to file at all, or HMRC has the wrong figures - say so clearly in your appeal and provide proof such as a filing receipt or correspondence. This is different from a reasonable excuse argument; here you are saying the penalty should never have been issued. Ask HMRC to cancel it and escalate to a review or tribunal if they refuse.
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