Key Dates for 2024/25 Tax Return (Due 2025/26)
| Deadline | Date | What it covers |
|---|---|---|
| Register for Self Assessment | 5 October 2025 | If you became self-employed in 2024/25 and haven't registered |
| Paper tax return filing | 31 October 2025 | 2024/25 tax return submitted by post |
| Online tax return filing | 31 January 2026 | 2024/25 tax return submitted online |
| Pay tax owed for 2024/25 | 31 January 2026 | Full payment of 2024/25 tax bill |
| First payment on account | 31 January 2026 | 50% advance payment toward 2025/26 tax bill |
| Second payment on account | 31 July 2026 | Remaining 50% advance toward 2025/26 tax bill |
⚠ January Double-Hit Warning
On 31 January 2026, you must pay both your 2024/25 tax bill and your first payment on account for 2025/26. For first-year filers, this can be up to 1.5× your annual tax bill in one payment. Budget early.
The Penalty Structure for Late Filing
HMRC's automatic penalties for missing the online filing deadline (31 January) are:
- 1 day late: £100 fixed penalty (applies even if you owe no tax)
- 3 months late: £10 per day, up to 90 days (maximum £900)
- 6 months late: Additional 5% of the tax owed, or £300 — whichever is greater
- 12 months late: Further 5% of the tax owed, or £300 — whichever is greater
This means a return filed 12 months late could incur penalties of £1,300+ on top of the tax owed — even if the return itself shows no tax due.
Penalties for Late Payment of Tax
Separate from late filing penalties, HMRC charges interest on unpaid tax from the payment deadline. Additionally:
- 30 days late: 5% surcharge on tax unpaid
- 6 months late: Further 5% surcharge
- 12 months late: Further 5% surcharge
The interest rate HMRC charges for late payment is the Bank of England base rate plus 2.5%. Always check HMRC's current rate at gov.uk.
What Happens If You Can't Pay?
If you genuinely cannot pay your tax bill in full, do not ignore it. Contact HMRC before the deadline and discuss a Time to Pay arrangement. HMRC allows monthly instalment plans for those who cannot pay in one go. Interest still accrues, but the penalty charges for non-payment are avoided.
Call HMRC's Self Assessment payment helpline: 0300 200 3822. Be prepared to explain your income, expenses, and what you can realistically afford to pay monthly.
Reasonable Excuse: How to Appeal a Penalty
HMRC will cancel a penalty if you have a reasonable excuse for filing or paying late. Acceptable reasons include:
- Serious illness (you or a close family member)
- Bereavement of a close relative shortly before the deadline
- A fire or flood that destroyed your records
- Technical failure of HMRC's own online system (HMRC issues notification when this occurs)
- Postal service failure (for paper returns)
Not acceptable: forgetting the deadline, not knowing you had to file, or being too busy.
To appeal, log in to your HMRC online account and use the appeals service, or write to HMRC with supporting evidence within 30 days of the penalty notice.
Avoid Penalties: Three Practical Tips
- Register in September, not October. Leave buffer time before the 5 October registration deadline. Your UTR arrives by post and takes up to 10 working days.
- File in November or December. Don't wait until January. The online system is slowest in late January as everyone files at once. Filing early does not mean you have to pay early — the payment deadline is still 31 January.
- Set aside 20-25% of net income monthly. A simple discipline: each time you receive payment from Uber, Deliveroo, or any platform, transfer 20-25% to a separate tax savings account. It prevents the January bill from being a shock.
Know Your Tax Bill Before January
Use our free calculator now to estimate what you'll owe in January — so you're never caught short on the deadline.
Open Free Tax Calculator →Frequently Asked Questions
I missed the January deadline. What should I do right now?
File immediately. The £100 penalty for day 1 is already charged if you're past 31 January, but every further day adds to the daily £10 penalties that start from 3 months. Filing now stops the daily penalties at whatever point you file. Do not compound the problem by continuing to delay.
If I owe no tax, do I still get a late filing penalty?
Yes. The £100 fixed penalty for filing after 31 January applies regardless of whether you owe any tax. Even a nil return filed late triggers the £100 charge.
What is payment on account and how is it calculated?
Payment on account is a system where HMRC asks you to pay 50% of your previous year's tax bill in advance by 31 January and another 50% by 31 July. This applies if your tax bill exceeds £1,000 and less than 80% was collected at source. In your first Self Assessment year, this can be a significant surprise — plan for it in advance.