Self Assessment Deadlines 2026/27: Every Date You Need

Missing a Self Assessment deadline triggers automatic penalties. Here is every date you need for the 2026/27 tax year.

The Essential Dates

| Date | What happens | |------|-------------| | 6 April 2026 | 2026/27 tax year begins | | 31 July 2026 | Second payment on account for 2025/26 due | | 5 October 2027 | Deadline to register for Self Assessment if newly self-employed in 2026/27 | | 5 April 2027 | 2026/27 tax year ends | | 31 October 2027 | Paper return deadline (if still eligible) | | 30 December 2027 | Deadline if you want HMRC to collect tax under £3,000 through your tax code | | 31 January 2028 | Online return deadline + payment due + first payment on account for 2027/28 | | 31 July 2028 | Second payment on account for 2027/28 |

MTD Quarterly Deadlines (If Applicable)

If you are within scope of MTD for Income Tax:

| Quarter | Covers | Due | |---------|--------|-----| | Q1 | 6 Apr – 5 Jul 2026 | 7 August 2026 | | Q2 | 6 Jul – 5 Oct 2026 | 7 November 2026 | | Q3 | 6 Oct 2026 – 5 Jan 2027 | 7 February 2027 | | Q4 | 6 Jan – 5 Apr 2027 | 7 May 2027 |

What Happens If You Miss a Deadline

Late filing: Automatic £100 penalty on 1 February, escalating to £10/day after 3 months, then percentage-based penalties at 6 and 12 months.

Late payment: 5% surcharge at 30 days, 6 months, and 12 months, plus daily interest.

Our Advice

File and pay as early as possible. You can submit your 2026/27 return from 6 April 2027 — waiting until January is unnecessary and risky. Accounted prepares your return throughout the year so you can file the moment the tax year ends.

Stop dreading your Self Assessment. Accounted tracks everything throughout the year so January is just a click, not a crisis. Try it free.