Overview
- Online Self Assessment returns are due by 31 January 2026, with fines starting at £100, then £10 per day after three months up to £900, plus further penalties of 5% of tax due or £300 at six and twelve months.
- Penalty notices issued for late filing or payment must be settled within 30 days of the date shown on the notice.
- Taxpayers can correct a submitted return within 12 months of the deadline, either online or by sending another paper return.
- HMRC says 4,606 returns were filed on Christmas Day and 37,435 across December 24–26, and customers who file by December 30 may be able to pay through their PAYE tax code.
- HMRC chief security officer Lucy Pike warned of scammers impersonating the tax authority and urged people to avoid clicking suspicious links or sharing personal details and to report doubtful contact to HMRC.