Self Assessment Deadline 31 January 2027: Paper Return 31 October 2026, Penalties and Payment Dates

HM Revenue and Customs (HMRC) must receive a paper Self Assessment tax return by 11:59pm on 31 October 2026, and the online return and the tax owed are both due by 11:59pm on 31 January 2027, according to the GOV.UK deadlines page. These dates are for the 2025 to 2026 tax year, which ran from 6 April 2025 to 5 April 2026. This story adds a weekday table, a computed calendar of the late filing penalties, and a one-page printable timeline.

What are the Self Assessment deadlines for 2025 to 2026?

GOV.UK sets four dates for this return. Two of them fall on a weekend, so check the day before you plan around them.

Deadline	Date	Weekday (our calculation)	What GOV.UK says
Paper return	31 October 2026	Saturday	HMRC must receive it by 11:59pm
Online return to pay through your tax code	30 December 2026	Wednesday	Submit it by 11:59pm
Online return	31 January 2027	Sunday	Submit it by 11:59pm
Pay the tax you owe	31 January 2027	Sunday	You must still pay by 11:59pm

Source: GOV.UK, Self Assessment tax returns: Deadlines, fetched 26 October 2026.

The paper deadline comes first, and GOV.UK says HMRC must receive the paper form by then. The January 2027 printable calendar shows where 31 January falls in the week.

Can I still register if I missed 5 October 2026?

GOV.UK says you must tell HMRC by 5 October 2026 if you need to complete a tax return, and that date has passed. The deadlines page says that if you register late, your deadline will be 3 months from the date on the letter or email HMRC sends you. We have no further detail on late registration from the pages we used.

What is the penalty for filing a Self Assessment return late?

GOV.UK lists these penalties for a late return:

• An initial £100 penalty if the return is up to 3 months late.
• After 3 months, £10 a day up to a maximum of £900.
• After 6 months, a further 5% of the tax due or £300, whichever is greater.
• After 12 months, another 5% of the tax due or £300, whichever is greater.

For late payment, GOV.UK lists 5% of the unpaid tax at 30 days, at 6 months and at 12 months, and says interest is charged on the amount owed.

What would the penalty calendar look like for 2027?

Here is the arithmetic if a return is not filed by 31 January 2027. These dates are our calculation from the GOV.UK rules, not an HMRC schedule, and HMRC decides the exact dates.

Step	Date (our calculation)	Weekday	Penalty under the GOV.UK rules
Return not filed by the deadline	From 1 February 2027	Monday	£100
3 months late	From 1 May 2027	Saturday	£10 a day starts
90 days of £10 reached	About 29 July 2027	Thursday	£900 daily maximum
6 months late	From 1 August 2027	Sunday	5% of tax due or £300, whichever is greater
12 months late	From 1 February 2028	Tuesday	5% of tax due or £300, whichever is greater
Tax unpaid 30 days	About 2 March 2027	Tuesday	5% of the unpaid tax

The daily charge is £900 divided by £10, which is 90 days, so the daily penalties run out about 29 July 2027 if counted from 1 May 2027. The £100 and the £900 together come to £1,000 before the 6-month charge applies.

What are payments on account and when are they due?

GOV.UK says payments on account are due by midnight on 31 January and 31 July, and that each payment is half of the tax you owed last year. Applied to this cycle, that means 31 January 2027 and 31 July 2027, a Saturday. GOV.UK says you do not need to make them if the tax you owed last year was less than £1,000. Check the GOV.UK payments on account page for the other conditions.

Printable

The timeline in the downloads below puts the deadlines and the penalty steps on one page. The printable yearly calendar shows the whole span from October 2026 to July 2027, and the 2026 UK holiday list shows the bank holidays around the 30 December date. For other UK money dates, see the UK Budget 2026 story, the Winter Fuel Payment story and the Cold Weather Payment story.