Millions of UK households are facing an immediate £100 penalty from HM Revenue and Customs (HMRC) if they fail to meet the fast-approaching self-assessment deadline on January 31.
The Race to Beat the Deadline
Fresh data reveals that over 54,053 people submitted their 2024/25 tax return over the New Year's Eve and New Year's Day period, with 342 even filing in the final hour of 2025. The busiest single hour was between 11am and 11.59am on December 31, when 3,927 returns were completed.
While more than 6.36 million people have already filed, HMRC reports that a significant 5.65 million individuals still need to complete their self-assessment forms before the cut-off. Myrtle Lloyd, HMRC’s chief customer officer, urged action: "New Year is a great time to start afresh. What better way than to ensure your tax affairs are in order... If you have yet to start, the clock is ticking."
Staggering Penalties for Late Returns and Payments
The consequences of missing the January 31 deadline are severe and escalate quickly. An initial £100 fixed penalty is applied automatically, even if you owe no tax or pay your bill on time.
The penalty structure for late filing is as follows:
- An immediate £100 fine.
- After 3 months, additional daily penalties of £10 per day, up to a maximum of £900.
- After 6 months, a further penalty of 5% of the tax due or £300, whichever is greater.
- After 12 months, another 5% or £300 charge, whichever is greater.
Separate penalties exist for late payment of any tax owed. Charges of 5% of the unpaid tax are applied at 30 days, 6 months, and 12 months. Interest is also charged on all overdue amounts.
Key Information and How to Avoid Penalties
HMRC offers comprehensive online guidance via GOV.UK to help people complete their returns. Taxpayers can start a return, save their progress, and return to it multiple times before submission. While payment for any outstanding tax does not need to be made immediately upon filing, it must be settled in full by the January 31 deadline.
For those liable for the High Income Child Benefit Charge (HICBC), a new option allows payment through your tax code via the PAYE digital service, removing the need to complete a full self-assessment return.
Pensioners should note that Winter Fuel Payments (or the Pension Age Winter Heating Payment in Scotland) received in 2025 do not need to be declared on the 2024/25 return. These will be addressed in the following year's submission.
HMRC advises using its official app to set up payment reminders and warns the public to be vigilant against fraudsters who often exploit the deadline period with fake communications. The tax authority stresses you should never disclose your login credentials to anyone.
Anyone who believes they cannot meet the deadline is encouraged to contact HMRC directly before January 31 to discuss their situation, as the body has committed to fair treatment for those with reasonable excuses.
