UK Self Assessment tax deadline approaches

HM Revenue and Customs (HMRC) is urging approximately 12 million taxpayers to prepare for the Self Assessment deadline on 31 January 2027. Filing early allows individuals to determine their tax liability sooner, budget more effectively, and secure refunds more quickly while avoiding potential penalties.

In the United Kingdom, late Self Assessment returns incur an automatic £100 penalty the day after the deadline, regardless of whether tax is owed. Additional penalties accrue at the three, six, and twelve-month marks. Specifically, after three months, daily penalties of £10 can apply up to a maximum of £900. At six and twelve months, further penalties of 5% of the tax due or £300 (whichever is greater) are applied.

Late payments are treated separately from late filings. HMRC applies penalties of 5% of the unpaid tax at 30 days, six months, and 12 months, alongside interest charges. As of early 2026, the late payment interest rate was reported at 7.75%, calculated based on the Bank of England base rate plus 4%.