HMRC issues urgent warning as £900 daily fines trigger for thousands

HM Revenue and Customs (HMRC) has issued an urgent directive to thousands of UK households who have yet to file their Self Assessment tax returns for the 2024/25 tax year. As of May 1, 2026, individuals who missed the original January 31 deadline have moved into a new penalty bracket, where daily fines of £10 are automatically applied, potentially totaling £900 by the end of this three-month window.

The warning comes as the tax authority seeks to clear a backlog of unfiled returns. While an initial £100 fixed penalty was applied immediately after the January deadline, the introduction of daily fines marks a significant escalation in HMRC's enforcement strategy for the current calendar year.

The Penalty Structure: How Fines Escalate

The UK tax system operates on a strict timeline for Self Assessment. For those who were required to file for the period ending April 5, 2025, the deadline for online submission was midnight on January 31, 2026. Once that window closes, the penalty clock begins to run according to a fixed schedule of increasing severity.

The current phase, which triggered on May 1, is often the most surprising for taxpayers, as the total fine can jump from £100 to over £1,000 in a matter of weeks if the return remains unfiled. HMRC officials have stressed that even if a taxpayer has no tax to pay, or has already paid the tax they owe, they can still be liable for these late-filing penalties.

Avoiding the 'Cliff Edge'

HMRC is urging anyone with an outstanding return to log into the GOV.UK portal or use the official HMRC app to complete their submission as soon as possible. 'The best way to stop the clock on these daily fines is to file today,' a spokesperson for the department said. 'We want to help people get their tax right and avoid unnecessary penalties, but we must also ensure that the system is fair for the millions who file on time.'

For those facing genuine hardship or who have a 'reasonable excuse' for the delay — such as a serious illness, a recent bereavement, or a failure in HMRC's own online services — it is possible to appeal the penalties. However, the authority notes that 'forgetting the deadline' or 'relying on an accountant who failed to file' are rarely accepted as valid reasons for an appeal.

Surge in Phishing Scams

Concurrent with the warning about genuine fines, HMRC has also alerted the public to a significant surge in phishing scams. Fraudsters are reportedly using the news of the £900 penalties to create a sense of panic, sending text messages and emails that appear to be from the tax office.

These messages often claim that the recipient is facing an immediate court summons or, conversely, that they are owed a significant tax refund. They typically include a link to a fake website designed to harvest personal data and banking credentials. HMRC has reminded taxpayers that they will never ask for personal or financial information via text or email, nor will they announce a tax refund in this manner.

Strategic Impact and Revenue

The enforcement of late-filing penalties is a critical component of the UK's fiscal management. By encouraging timely compliance, HMRC ensures a steady flow of revenue to fund public services. Analysts suggest that the high number of late filers this year may be due to a combination of post-election policy changes and the increasing complexity of the 'side-hustle' tax rules, which brought many more small-scale earners into the Self Assessment net for the first time.

What Taxpayers Should Do Now

If you believe you may have an outstanding return, your first step should be to verify your status through the official HMRC online account. Do not wait for a letter to arrive, as the daily fines accrue regardless of whether you have seen the notification. If you are struggling to complete the form, HMRC provides a range of digital assistants and telephone helplines, though wait times are expected to increase as the six-month penalty threshold approaches in July.

The department also offers 'Time to Pay' arrangements for those who have filed their return but are unable to pay the tax bill itself. This can help prevent further interest charges, though it does not usually waive the late-filing penalties themselves. As the May deadline for the start of daily fines passes, the message from HMRC is clear: the cost of delay is rising every day, and the most expensive action is doing nothing at all.