Short answer: If you file your Self Assessment tax return late, HMRC charges an automatic £100 penalty the day after the deadline even if you owe no tax or have already paid. The longer you leave it, the more it grows: daily charges kick in after 3 months, and further percentage-based penalties apply at 6 and 12 months. Late payment penalties and interest are charged separately on top. If you’re already late or worried about a deadline, book a free consultation with ATB Solutions and we’ll help you limit the damage.
The Self Assessment deadlines you can’t miss
Penalties are triggered by missing these dates, so it helps to have them clear:
- Register for Self Assessment: by 5 October after the end of the tax year you need to report.
- Paper tax return: midnight on 31 October.
- Online tax return: midnight on 31 January.
- Pay the tax you owe: 31 January (plus payments on account on 31 January and 31 July, if they apply to you).
The tax year runs 6 April to 5 April, so a 2024/25 return is due online by 31 January 2026. Miss it by a single day and the first penalty applies automatically.
HMRC late filing penalties: the full ladder
Late filing penalties escalate in stages under Schedule 55 of the Finance Act 2009. Each stage is added on top of the last:
| How late the return is | Late filing penalty |
|---|---|
| 1 day late | £100 fixed penalty — applies even if you owe no tax |
| 3 months late | £10 per day for up to 90 days (maximum £900), on top of the £100 |
| 6 months late | A further 5% of the tax due or £300 — whichever is higher |
| 12 months late | Another 5% of the tax due or £300 — whichever is higher |
These charges stack. A return that is a full 12 months late can rack up at least £1,600 in filing penalties (£100 + £900 + £300 + £300) — before any tax, interest, or late payment penalties are even counted.
Does the £100 penalty apply if I owe no tax?
Yes — and this is the point that catches most people out. The £100 fixed penalty and the £10-per-day daily charges are triggered by the return being late, not by whether you owe anything. If your return shows a refund or a nil balance, you still get penalised for filing late. The 6-month and 12-month percentage penalties are based on the tax due, so those may be lower or nil if you owe nothing — but the earlier fixed penalties still stand. Filing on time, every time, is the only way to avoid them, which is exactly what our Self Assessment tax return service is built around.
Late payment penalties are separate from late filing
Filing your return and paying your tax are two different obligations, each with its own penalties. If you pay the tax you owe late, HMRC charges:
- 5% of the unpaid tax at 30 days late
- A further 5% at 6 months late
- Another 5% at 12 months late
On top of these, interest accrues daily on any unpaid tax from 1 February at HMRC’s published rate until the balance is cleared. Because the rate tracks the Bank of England base rate, it’s worth checking the current figure rather than assuming — or letting us model it for you.
A quick worked example
Say you owe £5,000 for the year and file and pay everything six months late. You could be looking at the £100 fixed penalty, up to £900 in daily penalties, a 6-month filing penalty (5% of £5,000 = £250, but the £300 minimum applies), plus a 5% late payment penalty (£250) and daily interest — comfortably more than £1,500 on top of the original bill. The maths gets worse the longer it runs.
Big change from April 2026 the points-based penalty system
The rules are shifting as Making Tax Digital for Income Tax Self Assessment (MTD for ITSA) rolls out. From 6 April 2026, self-employed people and landlords with qualifying income over £50,000 must keep digital records and send quarterly updates to HMRC. The threshold falls to £30,000 from April 2027 and £20,000 from April 2028.
For those inside MTD, late submissions move to a points-based system instead of an instant fine. You collect a point each time you file late, and a £200 penalty is charged only once you hit the threshold for your filing frequency. Each further late submission after that is another £200. Points expire after 24 months of good compliance. A first-year easement applies to the initial quarterly updates, but penalties still bite for late final declarations and late payment. If you’re unsure whether MTD applies to you yet, our team can check your income against the thresholds — start with a free consultation.
What about companies? Corporation Tax and Companies House
If you run a limited company, late filing penalties work differently and can come from two directions: HMRC for a late Company Tax Return (CT600) and Companies House for late statutory accounts, each with its own escalating charges. We cover both under our Corporation Tax & CT600 service and annual accounts service, so nothing slips through the gaps. VAT has its own separate points-based late submission regime too, which we handle through our VAT return service.
Can you appeal an HMRC late filing penalty?
Yes. You normally have 30 days from the date of the penalty notice to appeal, using form SA370, your online HMRC account, or by post. To succeed, you need a “reasonable excuse” — a genuine, unforeseen event that stopped you filing on time. HMRC gives examples such as a serious illness, a bereavement close to the deadline, or a technical failure of its own systems. A simple oversight, being too busy, or not understanding the rules is unlikely to succeed on its own. If you can’t pay, setting up a Time to Pay arrangement before the 30-day point can prevent the first late payment penalty.
How to avoid late filing penalties altogether
- Register early if it’s your first return — the UTR can take time to arrive.
- Keep records as you go rather than scrambling in January. Our free Self-Assessment checklist and worksheets make this easy.
- File well before 31 January to avoid the late-month HMRC system rush.
- Hand it to an accountant who tracks your deadlines for you. At ATB Solutions, every deadline is monitored and filings go in on time — our sole trader package starts at £60/month.
Already late or dreading the deadline? Talk to us
Whether you’ve just missed a deadline or you want to make sure you never do, ATB Solutions can help you file correctly, minimise penalties, and deal with HMRC on your behalf. We support sole traders, landlords, contractors and limited companies across Birmingham and the West Midlands. Book your free consultation, call 07754 165406, or get in touch here.
This article is general information, not personal tax advice. Penalty rules and rates change — for guidance on your own situation, please contact ATB Solutions.
Frequently Asked Questions
What is the penalty for filing a tax return late in the UK?
HMRC charges an automatic £100 fixed penalty the day after the 31 January online deadline. If the return is still not filed after 3 months, £10 per day applies for up to 90 days (maximum £900), followed by further penalties of 5% of the tax due or £300 (whichever is higher) at 6 months and again at 12 months.
Do I still get fined if I don’t owe any tax?
Yes. The £100 fixed penalty and the daily penalties are triggered by the return being late, not by whether tax is owed. Even a nil or refund return incurs the £100 charge if filed late.
Are late filing and late payment penalties the same thing?
No. They are separate. Late filing penalties relate to the return not being submitted. Late payment penalties (5% at 30 days, then 5% at 6 months and 5% at 12 months) plus daily interest apply to tax that is paid late.
How do I appeal an HMRC late filing penalty?
Appeal within 30 days of the penalty notice using form SA370, your HMRC online account, or by post. You need a reasonable excuse — a genuine unforeseen event that prevented timely filing, such as serious illness or bereavement. Simple oversight rarely succeeds.
What is changing with penalties from April 2026?
As Making Tax Digital for Income Tax rolls out to self-employed people and landlords earning over £50,000, late submissions move to a points-based system. You accrue points for late filing and only pay a £200 penalty once you reach the threshold, with points expiring after 24 months of compliance.
Can an accountant help reduce my penalties?
Yes. An accountant can file outstanding returns quickly to stop penalties escalating, help you claim a reasonable excuse where one applies, set up a Time to Pay arrangement, and keep future deadlines on track. ATB Solutions offers a free consultation to review your position.
