Tax Return Deadlines You Need to Know
Keeping track of tax return deadlines is important if you are self-employed, a landlord, a business partner or anyone else who needs to complete a Self Assessment tax return in the UK. Missing a deadline can lead to penalties, interest and extra work, even if you have little or no tax to pay.
For the 2025 to 2026 tax year, which ran from 6 April 2025 to 5 April 2026, there are several important dates to remember. These include the deadline for registering for Self Assessment, the paper return deadline, the online filing deadline and the dates when tax payments are due. Understanding these dates now can give you more time to prepare your records and avoid a last-minute rush.
5 October 2026: Register for Self Assessment
If you need to complete a Self Assessment tax return for the 2025 to 2026 tax year and have not previously registered, you will normally need to tell HM Revenue and Customs by 5 October 2026. This can also apply if you registered in the past but did not need to send a return for the previous tax year. Registering early gives you more time to receive the information you need and prepare your return before the filing deadline.
If you register after 5 October 2026, HM Revenue and Customs may give you a different filing deadline. This will normally be three months from the date shown on the letter or email that tells you to complete a return.
However, registering late does not automatically extend the deadline for paying your tax. Tax due for the 2025 to 2026 tax year will generally still need to be paid by 11:59pm on 31 January 2027.
Leaving registration until the last moment can also make it harder to deal with missing records or questions about your tax position, so it is sensible to check whether you need to register well before October.
31 October 2026: Paper Tax Return Deadline
If you are completing your Self Assessment return on paper, HM Revenue and Customs must normally receive it by 11:59pm on 31 October 2026. The date refers to when the return is received, rather than the date you put it in the post, so allow enough time for delivery.
The paper deadline is three months earlier than the standard online deadline. If you miss the paper deadline, you may still be able to complete the return online by 31 January 2027 instead, provided you are able to use the online service. There are separate rules for some taxpayers who cannot file online.
30 December 2026: Paying Through Your Tax Code
There is another useful date to remember if you want certain Self Assessment tax debts collected through your tax code. Your online return normally needs to be submitted by 11:59pm on 30 December 2026 for this option to be considered. Conditions apply, so submitting by this date does not guarantee that the amount can be collected in this way. If you miss the deadline, you will need to use another accepted payment method.
31 January 2027 is the main date most taxpayers need to remember. Your online Self Assessment return for the 2025 to 2026 tax year must normally be submitted by 11:59pm on that date.
Your balancing tax payment for the year is also normally due by 11:59pm on 31 January 2027. If payments on account apply to you, your first payment towards your 2026 to 2027 tax bill will usually be due on the same date.
You do not have to wait until January to submit your return. Returns for the 2025 to 2026 tax year could be filed from 6 April 2026, giving taxpayers almost ten months to complete the process before the online deadline.
How Many People Leave Their Tax Return Until January?
Recent figures show just how busy the final weeks of the Self Assessment season can become. For the 2024 to 2025 tax year, 12,029,168 Self Assessment returns were expected. By 31 January 2026, 11,489,825 returns had been received, including expected returns, voluntary returns and late registrations. An estimated one million customers missed the deadline.
Online filing now accounts for the great majority of returns. Of the returns received by the January 2026 deadline, 11,173,825 were filed online, representing 97.25% of returns after adjustments. Only 316,000 were paper returns. A total of 475,722 taxpayers filed on 31 January itself, including 27,456 who submitted their return during the final hour of the day. These figures show why completing a return before the final day can reduce unnecessary pressure.
31 July: Do You Need to Make a Payment on Account?
Some people who use Self Assessment also make payments on account towards their next tax bill. These normally involve two payments each year, with the first due on 31 January and the second due on 31 July. Each payment is usually equal to half of the relevant tax bill from the previous year.
Payments on account will generally not be required if the relevant tax owed for the previous year was less than £1,000, or if more than 80% of the tax was already collected outside Self Assessment. Your Self Assessment account will show whether payments on account apply to you and how much you need to pay.
What Happens If You Miss a Tax Return Deadline?
Missing the filing deadline can become expensive. Under the current rules, an online Self Assessment return submitted after its deadline can result in an initial £100 penalty. This can apply even if you have no tax to pay or have already paid the tax that you owe.
If the return remains outstanding for three months, further penalties of £10 per day can be charged for up to 90 days, creating an additional penalty of up to £900. At six months, a further charge can apply of 5% of the tax due or £300, whichever is greater. A further charge can apply after 12 months.
Late Payment Can Lead to Separate Charges
Filing your return and paying your tax are separate responsibilities. Completing the return by the deadline does not protect you from charges if the tax itself is paid late.
Under the current rules, late payment penalties can be charged at 5% of the unpaid tax after 30 days, six months and 12 months. Interest can also be added to overdue tax. If you cannot afford to pay the full amount, it is important not to ignore the bill. Depending on your circumstances, you may be able to arrange a payment plan with HM Revenue and Customs.
Why Filing Your Tax Return Early Can Help
There is no need to wait until January to complete a tax return. Filing earlier gives you more time to check your records, correct mistakes and understand how much tax you will need to pay. If you are due a tax refund, submitting your return earlier may also allow you to receive it sooner.
More taxpayers are choosing this approach. A record 737,891 people submitted their 2025 to 2026 Self Assessment return during April 2026. Of those, 298,905 filed during the first week of the new tax year. This means hundreds of thousands of taxpayers dealt with their return many months before the January 2027 deadline.
Keep These Tax Return Dates in Your Calendar
For the 2025 to 2026 tax year, the main dates to remember are 5 October 2026 for registration, 31 October 2026 for most paper returns, 30 December 2026 if you want eligible tax collected through your tax code, and 31 January 2027 for online returns and the main tax payment.
If payments on account apply to you, remember that there is also normally a payment deadline on 31 July. Your own circumstances may affect what you need to report or pay, so checking your position well before each deadline can help prevent unexpected penalties and interest.
Keeping on top of your tax return can make the process much easier. If you need support preparing and submitting your Self Assessment return, professional help can give you more time to focus on your work while making sure important deadlines are not overlooked.
Get help with your tax returns in Wakefield and the surrounding areas of West Yorkshire.