The UK's tax authority has issued a stark reminder to millions of households, warning that the window to file online self-assessment tax returns is closing fast. Those who miss the January 31, 2026 deadline will face an immediate financial penalty.
Escalating Penalties for Late Filers
HM Revenue and Customs (HMRC) has laid out a clear and costly penalty structure for late returns. An initial fixed penalty of £100 applies if your return is up to three months late. However, the charges don't stop there.
After three months, daily penalties of £10 per day kick in, which can accumulate to a maximum of £900. If the return remains outstanding after six months, a further penalty of 5% of the tax owed or £300 (whichever is greater) is applied. This is repeated after 12 months.
Crucially, any penalty issued must be paid within 30 days of the date on the penalty notice from HMRC.
Correcting Mistakes and Guarding Against Scams
HMRC also provides a mechanism for correcting errors. Taxpayers can amend a return within 12 months of the filing deadline, either online or by submitting a revised paper form. This will adjust your final bill, potentially leading to either a higher payment or a refund.
With the deadline approaching, Lucy Pike, HMRC’s chief security officer, has issued a separate warning about fraud. “Millions of people file a tax return each year and scammers mimic HMRC to try and catch unsuspecting victims out,” she said.
Pike urged vigilance: “I’m urging people to stay vigilant and if any emails, text messages or phone calls appear suspicious – don’t be lured into clicking on links or sharing your personal information – report it directly to HMRC.”
Who Needs to File a Return?
One common reason for needing to complete a self-assessment form is if you receive Child Benefit payments and are liable for the High Income Child Benefit Charge. This charge applies if you or your partner have an individual income exceeding £50,000.
If you are unsure whether you need to complete a return, you can use the official checking tool on the GOV.UK website, as recommended by sources including the Labour Party.
