Late filing penalties
For the 2025/26 tax year, an online return is late if it's not filed by 31 January 2027 (31 October 2026 for paper).
| How late | Penalty |
|---|---|
| 1 day late | £100 fixed penalty |
| 3 months late | £10 per day, for up to 90 days (maximum £900) |
| 6 months late | 5% of the tax due or £300, whichever is greater |
| 12 months late | Another 5% of the tax due or £300, whichever is greater |
That means a return filed 12 months late can cost at least £1,600, even if you owe little or no tax. Larger penalties can apply if HMRC thinks you deliberately withheld information.
Late payment penalties
Tax for 2025/26 is due by 31 January 2027. If it's still unpaid:
| How late | Penalty |
|---|---|
| 30 days late | 5% of the unpaid tax |
| 6 months late | Another 5% of the unpaid tax at that date |
| 12 months late | Another 5% of the unpaid tax at that date |
Setting up a payment plan before a penalty date can stop that penalty being charged.
Interest on late payments
HMRC also charges interest on unpaid tax, and on unpaid penalties, from the date it was due until it's paid. From 6 April 2025, the late payment interest rate is the Bank of England base rate plus 4%. HMRC publishes the current rate on GOV.UK.
Example: what a late return costs
Priya owes £2,000 for 2025/26. She files and pays on 15 August 2027 — about six and a half months late.
| Penalty | Amount |
|---|---|
| Late filing: initial | £100 |
| Late filing: daily (90 days × £10) | £900 |
| Late filing: 6 months (greater of 5% of £2,000 or £300) | £300 |
| Late payment: 30 days (5% of £2,000) | £100 |
| Late payment: 6 months (5% of £2,000) | £100 |
| Total penalties | £1,500, plus interest on the £2,000 |
That's 75% on top of the tax itself. Filing on time — even if you can't pay — removes most of it.
Appealing a penalty
You can appeal if you had a reasonable excuse — something unexpected outside your control that stopped you meeting the deadline, such as serious illness, a bereavement, or a failure of HMRC's online service. You generally need to appeal within 30 days of the penalty notice and still file the return.
Forgetting, not having the money, or relying on someone else who let you down usually aren't accepted on their own.
How to avoid penalties
- File as early as you can after 6 April — the deadline is 31 January but you don't need to wait.
- If you can't pay, still file on time and set up a payment plan.
- Make sure HMRC has your current address and email.
- Register by 5 October if it's your first year — see registering.
Start your return on TaxGo: upload your documents, answer what's missing and have it ready long before January. See all key dates on our deadlines page.