Less Than Two Months Until the Self Assessment Filing Deadline

This update is for UK Self Assessment taxpayers who are approaching the filing deadline and are unsure whether they still have time to submit their return without running into penalties.

With less than two months remaining before the 31 January deadline, it is important to understand what action is still possible, what happens if you miss the deadline, and why delaying further can create unnecessary problems.

Self-Assessment Filing and Payment Obligations Due by 31 January 2026

There are now less than 2 months to the self-assessment filing deadline for submissions of the 2024-25 tax returns. We urge our readers who have not yet completed and filed their 2024-25 tax return to act as soon as possible to avoid the stress of last-minute preparations as the 31 January 2026 deadline fast approaches, particularly those who may also be affected by Making Tax Digital requirements and rely on an MTD service in London for ongoing compliance.

You should also be aware that payment of any tax due should also be made by this date. This includes the remaining self-assessment balance for the 2024-25 tax year, and the first payment on account for the 2025-26 tax year.

Earlier this year, more than 11.5 million people submitted their 2023-24 self-assessment tax returns by the 31 January deadline. This included 732,498 taxpayers who left their filing until the final day and almost 31,442 that filed in the last hour (between 23:00 and 23:59) before the deadline!

There is a new digital PAYE service for the High Income Child Benefit Charge (HICBC). This allows Child Benefit claimants who previously used self-assessment solely to pay the charge to opt out and instead pay it through their tax code.

If you are filing online for the first time you should ensure that you register to use HMRC’s self-assessment online service as soon as possible. Once registered an activation code will be sent by mail. This process can take up to 10 working days.

What the Self Assessment Deadline Means

The Self Assessment filing deadline applies to anyone required to submit a tax return for the relevant tax year. HMRC expects the return to be filed online by 31 January, regardless of whether tax is owed or already paid.

Filing close to the deadline does not change the rules, but it does reduce the time available to correct mistakes, deal with missing information, or resolve unexpected issues.

Why Acting Now Matters

As the deadline approaches, pressure increases. HMRC systems are busier, professional support becomes harder to secure at short notice, and simple errors are more likely when returns are rushed.

Submitting your return now gives you clarity over your tax position and leaves time to address any problems before penalties apply.

Penalties If You Miss the Filing Deadline

If your Self Assessment tax return is filed late, HMRC will normally issue an automatic £100 penalty, even if no tax is due or the tax is paid on time.

If the return remains outstanding, daily penalties of £10 per day can apply after three months, followed by further penalties at six and twelve months. Late payment interest may also be charged on any unpaid tax.

In Practice – What We Commonly See

In practice, many taxpayers delay filing because they believe there is still “plenty of time”. We often see this result in rushed submissions, missed information, or penalties that could have been avoided by acting a few weeks earlier.

HMRC Guidance on Filing Deadlines

HMRC’s official guidance on Self Assessment deadlines and late filing penalties is available on
GOV.UK.

Do You Still Have Time to File?

If you haven’t yet filed your Self Assessment tax return, there may still be an opportunity to submit it correctly before the deadline — but the scope for mistakes is narrowing. For taxpayers in Hammersmith and nearby areas such as Askew Village and Goldhawk Road, a brief review with CIGMA Accounting can help confirm your current position and clarify what steps need to be taken next.