What Counts as a Reasonable Excuse for a Late Tax Return? Real Examples

What HMRC says counts

Examples HMRC recognises include the death of a partner or close relative shortly before the deadline, a serious or life-threatening illness, an unexpected stay in hospital, a fire, flood or theft that stopped you filing, and a failure of HMRC online services.

What usually does not count

Forgetting the deadline, being too busy, a cash flow problem on its own, or relying on someone else who let you down are generally not accepted. Not knowing about the deadline is also unlikely to succeed.

Evidence that helps

Dates matter. Keep letters, medical notes, insurance claims, screenshots of errors and anything showing when the problem started and ended. Explain what you did to file as soon as possible afterwards.

How to appeal

You can appeal online or by letter within 30 days of the penalty notice. If HMRC refuses you can request a review and, if needed, take the case to the tax tribunal.

What HMRC means by a reasonable excuse

A reasonable excuse is something that stopped you from meeting a tax obligation despite you taking reasonable care to do so. HMRC looks at what a sensible person in your position, who cared about meeting their obligations, would have done. The excuse has to be a real event or circumstance outside your control, and it has to cover the entire period of the delay. Not having enough money to pay the tax is generally not accepted as an excuse for late payment on its own, although there may be other help available. The same applies to simple forgetfulness or relying on someone else who then failed to act.

Examples that may be accepted

HMRC considers each case on its own facts, and no example guarantees success. Situations that are commonly put forward include:

• a serious or sudden illness or hospital stay, including a serious mental health condition, that stopped you dealing with your tax affairs;
• the death of a spouse, partner or close relative shortly before the deadline;
• a fire, flood or theft that destroyed your records;
• a failure of HMRC’s online systems or a software failure that you can evidence;
• postal delays where you posted a paper return in good time.

Examples that are normally not accepted include being too busy, being unaware of the deadline, finding the software difficult, or leaving things until the last minute. For more on the wider penalty regime, read late payment penalties explained.

What you must do once the excuse ends

A reasonable excuse does not last forever. Once the event that stopped you has ended, you need to file the return or pay the tax without unreasonable delay. HMRC often treats about 14 days after the problem ends as a guide, but check current HMRC guidance. If you wait months after recovering from an illness before filing, the excuse is unlikely to cover the whole period.

Worked example: how penalties can build up

This is an illustrative example. Someone’s return and payment for 2024/25 are due on 31 January 2026. They file seven months late, and the tax due is £4,000, none of which has been paid on time.

Interest on the unpaid tax is charged on top, at Bank Rate plus 4%. If a reasonable excuse is accepted for the whole delay, the penalties can be cancelled, but interest on late payment normally remains payable. This shows why acting early matters, even if you plan to appeal.

How to make the appeal

You can usually appeal a penalty online or by letter, normally within 30 days of the penalty notice. Explain clearly what happened, give dates, say how it prevented you from filing or paying, and attach evidence such as hospital letters, death certificates, insurer correspondence or error screenshots. State when the problem ended and when you then filed or paid. If HMRC rejects the appeal, you can ask for a review and, if necessary, take the matter to the tax tribunal. Our guide to how to appeal an HMRC penalty goes through the steps. If you are behind with your return, see late Self Assessment tax return help. If you cannot pay in full, you may be able to agree a payment plan: Time to Pay arrangements are generally available for debts under £30,000.

Common mistakes

• Delaying the appeal beyond the 30-day period without explaining why.
• Giving a vague account with no dates or evidence.
• Relying on an excuse that ended months before the return was filed.
• Not filing the return while the appeal is pending, which lets penalties keep building.
• Blaming an agent or accountant without checking whether HMRC will accept that position.

Practical checklist

1. Write a timeline of events and dates.
2. Collect evidence for each key date.
3. File the return and pay what you can straight away.
4. Submit the appeal within 30 days of the penalty notice.
5. Keep copies of everything you send.

How SATR can help

SATR, a trading style of Accotax, has qualified UK accountants who can prepare an overdue return and file it online for a fixed fee from £199 + VAT, so the penalties stop growing. You can order online.

This article is general information, not personal tax advice.

Frequently asked questions

How long do I have to appeal a penalty?

Normally 30 days from the date on the penalty notice, though late appeals can be accepted with a good reason.

Do I need an accountant to appeal?

No, but an accountant can present the facts clearly and often improves your chances.

Tax rules and rates change. Figures here reflect 2025/26 guidance; always check current HMRC rules or ask us before acting.

Is a busy period at work a reasonable excuse?

Generally not. Being busy or forgetting the deadline is not usually accepted, although a genuine and serious event outside your control may be.

Can I appeal a late payment penalty as well as a filing penalty?

Yes, both can be appealed if you have a reasonable excuse. Interest on late payment normally remains due, even where penalties are cancelled.

How long do I have to appeal?

Usually 30 days from the date of the penalty notice. If you are late, explain why in your appeal and check current HMRC guidance.

Related guides

• Self Assessment Deadline 31 January 2027: Preparation Plan
• What to Do If HMRC Opens an Enquiry Into Your Tax Return
• How to Claim a Self Assessment Tax Refund
• penalty appeals