The Self Assessment deadline was 31 January 2026. If you missed it, the clock is already ticking on penalties — but how bad is it, and what can you do right now to limit the damage?
This guide explains exactly what HMRC will charge you, when things get worse, and how to act fast to keep your penalty bill as low as possible.
What Happened the Day After 31 January?
The moment you missed the deadline, HMRC automatically issued a £100 fixed penalty. This applies even if:
- You have no tax to pay (or HMRC owes you a refund)
- You had a very small amount of tax due
- It was your first late return
There are no exceptions unless you have a reasonable excuse (more on that below).
The HMRC Penalty Timeline
Here is exactly how penalties escalate the longer you delay:
| Time After Deadline | Penalty | Notes |
|---|---|---|
| Day 1 (1 Feb 2026) | £100 fixed | Automatic, no exceptions |
| 3 months (1 May 2026) | +£10/day | Up to 90 days = up to £900 more |
| 6 months (1 Aug 2026) | +5% of tax due (min £300) | On top of earlier penalties |
| 12 months (1 Feb 2027) | +5% of tax due (min £300) | On top of everything above |
Example: If you owe £2,000 in tax and file 6 months late, you could face:
- £100 (initial fixed penalty)
- £900 (£10/day for 90 days)
- £300 (5% of £2,000, minimum £300)
- Total penalties: £1,300 — on top of the £2,000 tax
The earlier you file, the less you pay.
What About Late Payment?
Filing late and paying late are separate. If you also missed the payment deadline, HMRC charges:
- 30 days late: 5% of unpaid tax
- 6 months late: Another 5%
- 12 months late: Another 5%
- Daily interest: Currently around 7.25% per year on the unpaid amount
If you genuinely cannot pay the full amount, contact HMRC now to set up a Time to Pay arrangement. This pauses further late payment penalties while you make a plan.
How to Appeal an HMRC Penalty
You can appeal the £100 penalty (and daily penalties) if you have a reasonable excuse. HMRC accepts:
- Serious illness (you or a close family member)
- Bereavement close to the deadline
- Serious computer or HMRC software failure
- Natural disasters or emergencies beyond your control
- Postal delays for paper returns
HMRC does not accept:
- “I didn’t know about the deadline”
- “I couldn’t afford an accountant”
- “I was too busy”
- “I didn’t receive my UTR in time” (unless genuinely HMRC’s fault)
To appeal, you must submit your return first, then appeal within 30 days of receiving the penalty notice. We handle HMRC appeals for our clients regularly — if you have a genuine excuse, it’s worth challenging.
Step-by-Step: What to Do Right Now
- File your return immediately — even if you cannot pay the tax yet. Filing stops the daily penalties from starting on 1 May 2026.
- Pay what you can — a partial payment reduces the interest and late payment penalties charged on the remaining balance.
- Set up a Time to Pay arrangement — call HMRC on 0300 200 3822 or apply online at gov.uk if you cannot pay in full. Arrangements are usually over 6–12 months.
- Check if you have a reasonable excuse — if something serious prevented you from filing, document it and appeal within 30 days of the penalty notice.
- Get an accountant — if your return is complex or you’re dealing with HMRC directly, professional help is worth every penny.
Can You Still File Now?
Yes — absolutely. The online Self Assessment portal remains open year-round. You can file your 2024/25 return at any point. The key dates now are:
- File by 1 May 2026 to avoid daily penalties starting (£10/day for up to 90 days)
- File by 1 August 2026 to avoid the 5% surcharge on tax owed
Every day you delay now costs you £10 from May. That’s real money — act fast.
How We Can Help
We handle late Self Assessment returns regularly. We can:
- File your return quickly (usually within 3–5 working days)
- Check if you qualify for a penalty appeal
- Negotiate a Time to Pay arrangement with HMRC
- Make sure you’re claiming all allowable expenses to reduce your tax bill
Our Late Self Assessment service costs £299 (one-off) — which often saves far more than that in penalties avoided.
Frequently Asked Questions
I filed late but I don’t owe any tax — do I still get a penalty?
Yes. The £100 late filing penalty applies regardless of whether you owe tax. HMRC’s position is that the return is still required on time. However, if you are owed a refund, filing promptly will accelerate your repayment.
I’m registered for Self Assessment but I didn’t need to file — what now?
If your circumstances changed (you stopped being self-employed, for example), you should have notified HMRC to deregister from Self Assessment. If you didn’t, you may still receive the penalty. Contact HMRC to request deregistration and explain the situation — penalties in this case are often cancelled.
Can my accountant file on my behalf even now?
Yes. We can file on your behalf as your authorised agent. We just need to be granted agent access through HMRC’s system — which we handle as part of our onboarding. We can usually have your return filed within 3–5 working days of receiving your documents.
Will HMRC take legal action for a late return?
For most late returns, HMRC issues financial penalties rather than taking legal action. However, if tax is owed and remains unpaid for an extended period, HMRC can take enforcement action. This is rare for first-time late filers — but the longer you leave it, the greater the risk.
HS Global Accountancy are based in Harrow, London. We specialise in Self Assessment for sole traders, landlords, contractors, and gig workers across the UK. Our Late Self Assessment service gets your return filed fast and handles any HMRC correspondence. Get a quote in 60 seconds.
