HMRC Warns Taxpayers On Self Assessment Fines

HMRC Warns Taxpayers On Self Assessment Fines
Charlotte Baroukh

Charlotte Baroukh

Tax Expert @ Pie

3 min read

Updated: 2 Jan 2026

3 min read

Updated: 2 Jan 2026

Millions of taxpayers across the United Kingdom are being urged by HM Revenue and Customs (HMRC) to ensure their Self Assessment tax returns and payments are filed on time to avoid escalating financial penalties. The department has warned that individuals required to file a Self Assessment return must do so by 11:59pm on 31 January.


Failure to meet this deadline can lead to a series of fines, which may start at £100 but rise to £300 or more if delays persist. With over 11 million people expected to submit tax returns this year, HMRC is highlighting the importance of timely compliance.

January Deadline for Self Assessment Returns

The annual Self Assessment deadline for online returns falls at the end of January, marking a critical cut-off for those required to report earnings outside the PAYE system.


Individuals who file by paper needed to submit their return by 31 October of the previous year. According to HMRC guidance, anyone who misses the paper deadline must now submit an online return before 31 January to avoid penalties.

Who Must File a Self Assessment Return?

HMRC requires a Self Assessment tax return from individuals who are self-employed and earned over £1,000 in the previous tax year, those who received income from property or investments not taxed at source, and individuals who must pay the High Income Child Benefit Charge outside PAYE.


Others who may be liable include those with capital gains or foreign income, or those acting as partners in business partnerships. HMRC provides an online tool for individuals to check if they need to file.

Penalties for Late Filing and Payment

The penalty regime for late Self Assessment returns is firm. A £100 fixed penalty is imposed immediately after the deadline passes. If the return remains outstanding three months past the cut-off, further daily penalties of £10 accrue for up to 90 days, reaching a maximum of £900.


After six months, an additional penalty of £300 or 5% of the tax due whichever is greater applies. A further £300 or 5% penalty is charged after 12 months if the return is still not filed.

Additional Interest and Charges

Taxpayers who do not pay their bill in full by the 31 January deadline will incur a 5% penalty on any tax outstanding 30 days after the due date.


HMRC may add further 5% penalties if the tax remains unpaid after six and then twelve months. Interest is also charged on overdue tax from the date it becomes due until it is paid in full, according to HMRC’s official interest rates policy.

Challenging an HMRC Penalty

Recipients of late filing or late payment penalties have the right to appeal if they believe there is a reasonable excuse for the delay. Common reasons accepted by HMRC include illness, bereavement, or technical issues beyond the taxpayer’s control.


Taxpayers typically have 30 days from the date of the penalty notice to submit an appeal, providing supporting evidence as required. The exact process may vary depending on tax type and employment status, with further details available in HMRC’s guidance.

Final Summary

The consequences of missing HMRC’s Self Assessment deadlines can become increasingly severe, with penalties that start at £100 but can quickly exceed £300, in addition to further percentage penalties and accruing interest.


With millions expected to file tax returns in January, HMRC’s reminders serve as a timely warning of the financial risks of late action. Taxpayers uncertain about their obligations are advised to check their status immediately and seek official guidance if unclear.


For those wishing to better understand their UK tax position and upcoming deadlines, tools such as the Pie app can help manage important reminders and tasks.

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