UK households are being urgently warned that fines for missing the imminent Self Assessment tax deadline could escalate to a staggering £1,600, as HM Revenue and Customs (HMRC) ramps up its penalty regime.
The Critical January Deadline
HMRC has confirmed that anyone required to complete a Self Assessment must submit their online tax return and pay any outstanding tax by 11.59pm on 31 January 2026. This deadline is specifically for online submissions; the deadline for paper returns passed on 31 October of the previous year, with those filers already facing penalties.
Myrtle Lloyd, HMRC’s Chief Customer Officer, urged taxpayers to act swiftly: "The Self Assessment deadline is less than one month away, and thousands of people have already paid their tax bill via the HMRC app. It is quick and easy to do, and you can also see your payment history. Search ‘download the HMRC app’ on GOV.UK to access the app and make your Self Assessment payment."
How Penalties Can Skyrocket to £1,600
The financial consequences of missing the deadline are severe and increase rapidly over time. The penalty structure is as follows:
- An initial £100 late filing penalty is applied immediately after the deadline.
- If the return is still outstanding after three months, daily penalties of £10 begin to accrue, up to a maximum of £900.
- After six months, a further penalty of 5% of the tax due or £300 (whichever is greater) is charged.
- At the 12-month point, another 5% or £300 charge is applied, which can bring the total potential fines for filing late to £1,600, excluding the tax owed.
Furthermore, separate penalties apply for late payment of the tax itself. A charge of 5% of the unpaid tax is applied 30 days after the due date, with additional 5% penalties at six and twelve months late.
Expert Warning on 'Heavy' Interest Charges
Money-saving expert Martin Lewis has highlighted the additional burden of interest on late payments. "If you miss it, you risk an £100 fine and crucially, 7.45% interest, a heavy rate of interest," he stated. "That's an annual rate of interest that will apply for each day that you're late to pay the actual tax."
HMRC stresses that these escalating penalties are entirely avoidable by submitting and paying on time. With the deadline fast approaching, taxpayers are being urged to organise their records and use HMRC's online services or official app to meet their obligations and avoid a costly start to the new year.
