The UK's tax authority, HM Revenue and Customs (HMRC), has issued a critical 14-day reminder to households across the nation, warning that failure to meet a key deadline could result in an immediate £100 penalty.
Key Dates for Your 2024/25 Tax Return
The focus is on the Self Assessment process for the tax year that ran from 6 April 2024 to 5 April 2025. HMRC has outlined a strict schedule that taxpayers must adhere to. If you are new to Self Assessment and have never submitted a return before, you must register by 5 October 2025.
For the submission itself, the deadlines are split. If you prefer to file a paper tax return, you must submit it by midnight on 31 October 2025. However, for the majority who file online, the final cut-off is midnight on 31 January 2026. This is also the date by which any tax owed for that year must be paid in full.
Who Needs to File and How to Check
HMRC has urged people who are uncertain about their obligations to use its free online checking tool. The tool helps determine if you need to complete a return for the 2024/25 period and assures users that it does not submit their details to HMRC automatically.
This is particularly important for those with additional streams of income beyond a regular salary. The government advises that if you earn money from activities like selling goods online, renting out a property, or even letting out part of your home, you should check whether you need to declare it.
Stiff Penalties for Missing Deadlines
The consequences of missing these deadlines are financially punitive. A flat £100 fine is applied automatically if your tax return is filed late, regardless of whether you owe any tax or not.
Furthermore, from April 2025, a new penalty structure for late submission and payment will take effect, based on how late you are and the amount of tax due:
- Submitting your return up to 15 days late incurs a penalty of 3% of the tax owed.
- If it is up to 30 days late, the penalty rises to 6%.
- For returns that are 31 days late or more, an additional 10% penalty is added on top of the initial charges.
If the tax bill remains unpaid after 12 months, further fees, charges, and interest will accumulate. An extra 10% penalty can be added for every subsequent year the payment remains outstanding. HMRC does state that taxpayers can appeal against a penalty if they have a reasonable excuse for the delay.
With the online deadline now clearly in sight for January 2026, HMRC's message is clear: check your status promptly and diarise the key dates to avoid unnecessary and costly fines.
