The deadline for submitting self-assessment tax returns is set for 11:59 pm on January 31, and HM Revenue and Customs (HMRC) has issued a clear warning: millions of households risk financial penalties if they miss this date.
Despite the looming deadline, many taxpayers have yet to complete their returns. HMRC emphasizes that even a one-day delay—from February 1 onwards—automatically triggers a £100 fine. This penalty applies unless there is a reasonable excuse or an arrangement has been made with HMRC for a delayed payment.
Myrtle Lloyd, HMRC’s Chief Customer Officer, urged taxpayers to act promptly, highlighting the ease of filing via the HMRC app. “Thousands have already paid their tax bill using the app, which is quick and user-friendly. You can also track your payment history there,” she said.
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While penalties begin with the initial £100 fine for late filing, further charges apply for unpaid tax, including additional fees of 5% of the outstanding amount at 30 days, six months, and 12 months after the deadline.
HMRC recognizes specific valid reasons for late submission, such as bereavement, serious illness, technical issues with software or HMRC services, postal delays, and difficulties related to disability or mental health. Taxpayers must provide evidence and submit their returns or payments as soon as possible in these cases.
However, common issues like bounced cheques, misunderstanding deadlines, or missing reminders do not qualify as reasonable excuses and will incur penalties.
To avoid fines, taxpayers should ensure their return is fully completed and submitted by clicking the ‘Submit’ button online. Confirmation emails are sent upon successful submission.
For those unable to pay their tax in full, HMRC offers Time To Pay arrangements for debts under £30,000, provided eligibility criteria are met. Payments can be made through multiple channels, including bank transfers, direct debit, or the HMRC app.
Taxpayers can use the self-assessment tax calculator on GOV.UK to estimate their liabilities for the 2025-2026 tax year and plan accordingly.
HMRC continues to see increased app usage, with nearly 340,000 people paying via the app since April 6, 2025, marking significant growth from the previous year.
Don’t delay—the January 31 deadline is fast approaching, and missing it could cost you £100 or more.