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Start filing →Missing the Self Assessment deadline feels stressful — but it is fixable. The most important thing to know is this: filing late is always better than not filing at all. Every day you delay adds to your penalty. The right move is to file as soon as possible.
What Are the Penalties for a Late Return?
| When you file | Penalty |
|---|---|
| 1 day – 3 months late | Automatic £100 fixed penalty |
| 3 – 6 months late | £10 per day (up to £900 additional) |
| 6 – 12 months late | 5% of tax owed, or £300 — whichever is greater |
| Over 12 months late | Further 5% or £300 penalty, potential investigation |
Can You Appeal a Late Filing Penalty?
Yes — HMRC will consider appeals if you had a reasonable excuse for filing late. Accepted reasons include:
- Serious illness (yours or a close family member)
- Bereavement of a close family member near the deadline
- HMRC system failure on the day of filing
- Unexpected hospital stay
- Natural disaster affecting your records
Not accepted: not knowing about the deadline, being too busy, problems with your accountant, or waiting for information from a third party.
To appeal: file your return first, then appeal the penalty through your HMRC online account or by writing to HMRC.
What to Do Right Now
File your return today
Filing stops the daily penalties from accumulating. Even if you cannot pay the tax owed immediately, get the return in. HMRC treats late filing and late payment as separate issues.
Pay what you can
If you cannot pay the full tax bill, pay as much as you can immediately to reduce interest charges. Contact HMRC about a payment plan (Time to Pay arrangement) for the remainder.
Appeal the penalty if you have grounds
Once filed, you can appeal the penalty through your HMRC online account. Do this promptly — appeals should be made within 30 days of the penalty notice.
File your late return right now
Start your return for free — you only pay when you're ready to submit.
Every day counts. The sooner you file, the lower your total penalty. SubmitFox submits directly to HMRC.
Common Questions
Yes. The £100 automatic penalty applies from the day after the deadline regardless of how late you are. However, filing even one day late means you avoid the escalating daily penalties that start at 3 months.
Yes, absolutely. File your return immediately even if you cannot pay. Late filing and late payment are penalised separately. Filing gets you out of accumulating filing penalties. For the payment, contact HMRC about a Time to Pay arrangement.
Unfortunately, not knowing about the requirement is not accepted as a reasonable excuse by HMRC. If you should have been filing, penalties still apply. The best approach is to file as soon as you realise and contact HMRC if there are outstanding years.
In extreme cases of persistent non-filing, HMRC can pursue criminal prosecution. However, for most late filers, the practical consequences are financial penalties and interest. Filing voluntarily — even very late — is treated much more favourably than HMRC having to pursue you.
File all outstanding returns as soon as possible. HMRC has a disclosure process for bringing your tax affairs up to date. Penalties will apply for each outstanding year, but voluntary disclosure is always treated more favourably than HMRC discovering the backlog.