To appeal an HMRC penalty, send HMRC an appeal within 30 days of the date on the penalty notice, online, on form SA370 or by signed letter, explaining the reasonable excuse that stopped you filing or paying on time. Online is much faster: in October 2026 HMRC estimated about three weeks for an online appeal, against July 2027 for one posted that month. You can appeal even after paying, and a late appeal can still be accepted if you had a good reason for missing the 30 days.
An HMRC penalty is not final when it lands. HMRC has to consider every appeal on its facts, and it turns on three things: getting it in within the time limit, showing a reasonable excuse that covered the whole period you were late, and putting things right as soon as the excuse ended.
Self Assessment penalties are the most common, so most of what follows uses them. Company, payroll and VAT penalties use different routes, which are set out further down. If you would rather hand the paperwork over, our penalty appeal service checks the notices and evidence and gives a fixed quote before any work starts.
The Three Ways to Appeal a Self Assessment Penalty
HMRC accepts a Self Assessment penalty appeal in three forms. Each one asks for the same information: who you are, which penalty you are disputing, and why you were late.
- 1Online. HMRC's appeal checker asks which penalty you received and for which tax year, then sends you to the online appeal service. You sign in, or create sign-in details, and HMRC receives the appeal straight away. Individuals can appeal online for 2021 to 2022 and later years. Partnerships and earlier years have to use the paper form.
- 2Form SA370 by post. The paper SA370 form has tick boxes for the common reasons and space for your explanation. Partnerships use SA371 instead. The form tells you to post it to Self Assessment, HM Revenue and Customs, BX9 1AS. Postal appeals are slow: in October 2026 HMRC estimated a reply by July 2027 for an appeal posted that month, against about three weeks online.
- 3A signed letter. If you have no form and cannot use the online service, a signed letter to the HMRC office that deals with your return works. Give your name, your Unique Taxpayer Reference, the penalty and the dates involved, and explain why the return or payment was late.
Whichever route you use, keep a copy and a record of the date you sent it. If you are unsure which notice to dispute, the Self Assessment helpline is 0300 200 3310, Monday to Friday, 8am to 6pm.
The 30-Day Appeal Deadline and Late Appeals
You usually have 30 days from the date the penalty was issued to appeal, according to HMRC's penalty appeal guidance. The clock runs from the date printed on the notice, not the day the letter reached you. Each penalty notice has its own 30 days, so the £100 penalty, the £10 a day charges and the later 6 and 12 month penalties each need appealing in time. The free appeal deadline checker works out the date for each notice.
Missing the 30 days does not end your options. Under section 49 of the Taxes Management Act 1970, HMRC must accept a late appeal if you had a reasonable excuse for appealing late and you then appealed without unreasonable delay. If HMRC refuses, the tax tribunal can still give permission for the appeal to go ahead. A late appeal therefore needs two explanations: why the return or payment was late, and why the appeal itself was late.
Filing and Paying While an Appeal Is Open
Send the overdue return first if you can. HMRC says it may not be able to progress a late filing appeal until the return is in, and every month it stays outstanding adds to the penalties. Filing on your best figures and correcting them later is usually better than waiting for perfect records.
Paying does not stop you appealing. HMRC suggests you consider paying while the appeal runs, because interest is charged from the original due date if you lose. If you win, HMRC repays the penalty with interest from the date you paid. HMRC's own manual says it normally holds the fixed £100 penalty once an appeal is logged, but that is practice rather than a right, so do not ignore other debt letters.
If you never needed to file
An appeal is the wrong route when you should not have been in Self Assessment for that year at all. In that case ask HMRC to withdraw the notice to file and cancel the penalty instead. You still need to act promptly once the penalty arrives.
Grounds HMRC Will Consider
Almost every appeal rests on a reasonable excuse: something outside your control that stopped you filing or paying on time despite taking reasonable care. HMRC's examples include the death of a partner or close relative shortly before the deadline, serious illness or a hospital stay, a computer or software failure while preparing the return, and fire, flood or theft. It does not accept finding the online system too difficult, not getting a reminder, or making a mistake on the return.
The law adds three limits. A shortage of money is not an excuse unless it came from events outside your control. Relying on someone else is not an excuse unless you took reasonable care, which matters when an accountant failed to file for you. And once the excuse ends, you must put things right without unreasonable delay. Tribunals often accept the excuse itself and then dismiss the appeal because months passed before the return went in.
Some appeals are not about an excuse at all. If the penalty is for the wrong year, the wrong amount, or a return HMRC already had on time, say so plainly and send the proof, such as the submission receipt.
Evidence and the Appeal Timeline
HMRC asks for the date the penalty was issued, the date you filed, the date you paid and the details of your excuse. The strongest appeals set these out as a dated timeline: when the problem started, how it stopped you meeting the deadline, when it ended, and what you did next. Gaps in that timeline are where appeals fail.
- Medical or hospital letters that give dates, not just a diagnosis.
- A death certificate or funeral details for a bereavement.
- Screenshots, error messages or submission receipts for a technical failure.
- Emails and dated instructions to an agent who was meant to file.
- Proof of posting, insurance claims or police reports for postal problems, fire, flood or theft.
You do not always have to send evidence with the appeal, but HMRC can ask for it, so gather it before you write. Do not guess dates. Mark anything approximate as approximate.
Corporation Tax, PAYE and VAT Penalty Appeals
Company penalties follow different rules. For Corporation Tax returns due on or after 1 April 2026, the fixed late filing penalties for a CT600 doubled to £200, then £400 once the return is more than three months late, with £1,000 and £2,000 for a third late return in a row. HMRC paused these notices while its systems were updated and began sending them again in August 2026, so some companies are receiving late notices now. The 30 days still runs from the date on the notice.
- Corporation Tax: file the company return first, then use HMRC's online appeal form, which you print and post, or write to the address on the penalty notice within 30 days.
- PAYE: appeal a late filing penalty inside HMRC's PAYE for employers service using the appeal a penalty option. Take a screenshot, as there is no print function.
- VAT: the penalty letter offers a review. Ask for it in your VAT online account, or appeal straight to the tax tribunal, within 30 days.
Penalty Points Under Making Tax Digital
Sole traders and landlords with qualifying income over £50,000 joined Making Tax Digital for Income Tax on 6 April 2026. They are on a points system rather than the £100 penalty. Each missed deadline adds a point, and reaching four points triggers a £200 penalty, with another £200 for each later miss. For 2026 to 2027, HMRC is not giving points for late quarterly updates, but a late tax return still earns one.
Each point arrives with its own letter, and you can appeal a point as well as a penalty. HMRC applies the same reasonable excuse test. Appealing a wrong point early stops it counting towards the £200 threshold later.
Review and Tribunal After a Rejection
If HMRC keeps the penalty, its letter offers a review by an officer who was not involved in the first decision. You have 30 days from that letter to accept the review or appeal to the First-tier Tax Tribunal instead. HMRC must finish a review within 45 days unless you agree longer, and if it misses that deadline the original decision is treated as upheld, which keeps your tribunal route open. There is no upfront fee to take a penalty appeal to the tribunal. The options after a rejected appeal depend on whether new evidence is available and how much is at stake.
Common Questions About HMRC Penalty Appeals
Can I appeal an HMRC penalty online?
Yes for most Self Assessment penalties, through HMRC's appeal checker and online service. PAYE penalties are appealed in the PAYE for employers service and VAT reviews in the VAT online account. Corporation Tax uses an online form that you print and post.
How long does HMRC take to decide an appeal?
It depends on how you send it. HMRC's reply-time tool gave an estimate of about three weeks for a Self Assessment appeal made online on 26 October 2026, and 12 July 2027 for one posted the same day. A review, once you accept one, has to be finished within 45 days.
Can I appeal if I have already paid the penalty?
Yes. Paying is not an admission. If the appeal succeeds, HMRC repays the penalty with interest from the date you paid.
Is it worth paying someone to appeal a £100 penalty?
Usually not for a single £100 penalty with a clear excuse, which you can appeal yourself online. Help becomes worthwhile when daily penalties and percentage penalties have stacked up across several years, or when an appeal has already been refused. Accountant fees for late returns vary with how many notices and years are involved.