What is the online Self Assessment deadline for 2026/27 in the UK?

Full answer

Self Assessment returns cover the UK tax year running from 6 April to 5 April. The 2026/27 tax year ends on 5 April 2027, and the key deadlines that follow are: Key Self Assessment deadlines for 2026/27 -- 5 October 2027: Register for Self Assessment if you are new to it (e.g., you became self-employed or received other untaxed income in 2026/27). -- 31 October 2027: Deadline for filing a paper tax return for 2026/27. -- 31 January 2028: Deadline for filing online and paying all tax owed for 2026/27, plus the first payment on account for 2027/28. -- 31 July 2028: Second payment on account for 2027/28. Payments on account If your Self Assessment tax bill is above GBP 1,000 and less than 80% was collected at source (via PAYE), HMRC requires payments on account -- two advance instalments of the following year's estimated tax. Each is 50% of the prior year's bill. They are due on 31 January and 31 July of the following year. Penalties for late filing or payment -- GBP 100 fixed penalty if the return is filed one day late, even if no tax is owed. -- Additional daily penalties of GBP 10/day after 3 months (up to GBP 900). -- Further 5% surcharges on unpaid tax at 6, 12, and 12+ months. -- Late payment interest applies immediately after 31 January 2028 on unpaid tax. Making Tax Digital for Income Tax (MTD ITSA) From April 2026 (i.e., from the 2026/27 tax year), self-employed people and landlords with income over GBP 50,000 must use MTD-compatible software to keep digital records and submit quarterly updates to HMRC. Annual finalisation replaces the traditional return for affected taxpayers. Those with income between GBP 30,000 and GBP 50,000 must comply from April 2027. Tips -- File well before 31 January 2028 to know what you owe and to avoid the last-minute rush. -- If you cannot pay, contact HMRC before the deadline to set up a Time to Pay arrangement -- penalties and interest still apply but HMRC takes a more lenient view if you engage proactively. -- Keep records for at least 5 years after the 31 January 2028 filing deadline.

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