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What is Self Assessment deadlines?
Last verified 23 October 2026
Self Assessment deadlines are the fixed dates by which you must register, file your tax return and pay Income Tax for a tax year. The main ones fall in the months after the tax year ends on 5 April.
Why it matters to landlords
If you need to file for the first time, for example because you have started letting, tell HMRC by registering by 5 October after the tax year. A paper return must reach HMRC by 31 October. An online return is due by 31 January, and so is any tax you owe. If you make payments on account, the second one is due by 31 July. If you register after 5 October, HMRC gives you 3 months from the date of its notice to file, but payment is still due by 31 January. If you want the tax collected through your PAYE tax code, file online by 30 December.
Under Making Tax Digital for Income Tax the return is still due by 31 January, but it is submitted through your software. Missing these deadlines can lead to penalties and interest.
Example
For the 2025 to 2026 tax year: register by 5 October 2026, file a paper return by 31 October 2026, or file online and pay by 31 January 2027.
How to submit your tax return digitally →