HM Revenue and Customs (HMRC) has warned that 12 million UK households who need to submit a Self Assessment tax return face a £100 late filing penalty if they miss the deadline on January 31, 2027. The tax office confirmed there are now just 100 days until the submission deadline and is urging households to file early to avoid the January rush.
Deadlines for paper and online returns
The January 31, 2027 deadline applies to people who file online, but those submitting a paper tax return must do so by 11.59pm on October 31, 2026, which is now just a week away. Regardless of the filing method, the deadline to submit the tax bill and pay what is owed for the tax year remains 11.59pm on January 31, 2027, giving households a few months to plan and budget for any tax due.
According to HMRC, around 12 million people are expected to submit a tax return for the 2025 to 2026 tax year by January 31. Those who fail to file in time face a fixed £100 late filing penalty, even if there is no tax to pay.
Benefits of filing early
HMRC says submitting tax returns early allows households to find out how much tax they owe before the deadline, giving them more time to budget. It also helps ensure tax returns are accurate, so individuals are not paying more tax than necessary. Filing early can also result in a quicker refund if too much tax has been paid, and crucially, it avoids a penalty for submitting a tax return late.
In a reminder on October 23, Myrtle Lloyd, HMRC’s Chief Customer Officer, said: “The Self Assessment deadline is 100 days away so now is the ideal time to get ahead and file your tax return early.” She added: “Guidance and support are available on GOV.UK to help you file your tax return. Just search ‘file my Self Assessment’ on GOV.UK to start yours today.”
Who needs to file a tax return
A tax return must be sent to HMRC if, in the last tax year from April 6 to April 5, any of the following applied: being self-employed as a ‘sole trader’ earning more than £1,000 (before taking off anything claimable as tax relief), being a partner in a business partnership, having to pay Capital Gains Tax when selling or ‘disposing of’ something that increased in value, having to pay the High Income Child Benefit Charge without paying it through PAYE, or being an off-payroll worker repaying a student or postgraduate loan. A tax return may also be needed if there is any untaxed income, such as money from renting out property, tips and commission, savings interest, dividends, or foreign income.
Failure to submit the tax return and pay any tax owed by January 31 results in a fixed £100 late filing penalty, even if there is no tax to pay. After three months, those who still haven’t filed face an additional penalty of £10 per day, up to a maximum of £900. After six months, a further penalty of 5% of the tax due, or £300 – whichever is higher – is added. After 12 months, another 5% – or £300 – is added. Interest is also charged on any unpaid tax after the deadline, in addition to the extra penalties.
Additional guidance and next steps
HMRC added: “Check the filing deadlines. The deadline for sending a paper return is before the deadline for an online return. You can send your return any time after 5 April. Sending it earlier means you: find out what you owe, can budget – if you want to make weekly or monthly payments, have time to pay your bill by 31 January, can set up a payment plan, if you do not think you can pay on time.”
People new to Self Assessment must first register to receive their Unique Taxpayer Reference, which is needed when completing and filing a return. Anyone who needs to tell HMRC that they no longer need to submit a tax return can do so on GOV.UK. Those signed up to Making Tax Digital for Income Tax still need to submit their Self Assessment tax return in the usual way and pay any tax owed by January 31, 2027. Self Assessment customers with a PAYE income can file online before December 30, 2026, and have any tax owed collected via their tax code.
