The main UK tax return deadline for the 2025/26 tax year is 31 January 2027 for taxpayers submitting their Self Assessment return online. Anyone filing a paper tax return normally needs to make sure HMRC receives it by 31 October 2026.
The 2025/26 tax year ran from 6 April 2025 to 5 April 2026. People filing for the first time normally needed to tell HMRC that they required Self Assessment by 5 October 2026. Tax due for the year must normally be paid by 11:59 pm on 31 January 2027.
This means someone searching for the tax return deadline during late 2026 is generally dealing with income received during the 2025/26 tax year, rather than income being earned during the current 2026/27 tax year.
How Is the Tax Return Deadline Calculated?
The Self Assessment deadline is based on the UK tax year rather than the calendar year. A UK tax year normally begins on 6 April and ends on 5 April of the following year.
For example, income earned between 6 April 2025 and 5 April 2026 belongs to the 2025/26 tax year. Once that year ends, taxpayers have several months to prepare their return.
Under the normal Self Assessment timetable, a paper return for that year must reach HMRC by 31 October 2026, while an online return must be submitted by 31 January 2027.
It can therefore be helpful to think of the calculation as:
| Stage | 2025/26 Tax Return |
|---|---|
| Tax Year Starts | 6 April 2025 |
| Tax Year Ends | 5 April 2026 |
| Registration Deadline | 5 October 2026 |
| Paper Filing Deadline | 31 October 2026 |
| PAYE Tax Code Filing Deadline | 30 December 2026 |
| Online Filing Deadline | 31 January 2027 |
| Tax Payment Deadline | 31 January 2027 |
| Second Payment On Account | 31 July 2027 |
Taxpayers should not calculate their deadline simply by counting a fixed number of months after they started working or became self-employed. The relevant tax year and the filing method usually determine the date.
How the Tax Year Determines the Deadline?
Self Assessment is completed after the relevant tax year has finished. Therefore, someone earning self-employed income during the 2026/27 tax year, which runs from 6 April 2026 to 5 April 2027, would normally deal with that return after 5 April 2027.
The normal online filing deadline for that tax year would be 31 January 2028.
MoneyHelper’s Self Assessment tax return guidance also explains that returns are filed for tax years rather than calendar years and normally submitted during the following financial year.
How Paper and Online Deadlines Are Calculated?
Paper filing has an earlier deadline because HMRC needs more time to process returns manually. For the 2025/26 tax year, HMRC must normally receive a paper return by 11:59pm on 31 October 2026.
Online taxpayers receive an additional three months, with the deadline falling at 11:59pm on 31 January 2027.
A taxpayer who intended to submit on paper but misses the October deadline may usually still submit the return online before the January deadline rather than sending a late paper return.
Will Every Tax Return Have the Same Time Period for the Deadline?
No. Although most individual Self Assessment taxpayers follow the standard October and January timetable, not every taxpayer will always have exactly the same filing period.
One important exception applies when someone registers for Self Assessment after 5 October 2026.
HMRC states that it will send the taxpayer a letter or email giving a different filing deadline, normally three months from the date of that communication. However, tax owed for 2025/26 will generally still need to be paid by 11:59pm on 31 January 2027.
Other exceptions also exist. Trustees of registered pension schemes and certain non-resident companies that cannot file online have a paper deadline of 31 January 2027.
Partnerships containing a limited company partner may also have deadlines linked to the partnership’s accounting date.
Therefore, 31 January is the normal online Self Assessment deadline, but taxpayers should not assume it applies identically in every situation.
What Are the Main Self Assessment Deadlines in 2026 and 2027?
For most taxpayers completing a return for 2025/26, the important dates are straightforward.
The registration deadline is 5 October 2026 for someone who needs to complete a return for the previous year and has not filed before, or who was previously registered but did not need a return for 2024/25.
Paper returns must normally reach HMRC by 31 October 2026.
Anyone who wants HMRC to consider collecting an eligible Self Assessment bill through their PAYE tax code needs to submit online by 30 December 2026.
The main online tax return deadline is 31 January 2027, and tax owed must normally also reach HMRC by that date. The official HMRC Self Assessment deadline rules confirm the 2026 and 2027 filing and payment dates.
Taxpayers making payments on account may then have another payment due on 31 July 2027.
It is also worth noting that 31 January 2027 falls on a Sunday.
HMRC says that where a payment deadline falls on a weekend or bank holiday, payments using methods that take several working days should normally reach HMRC on the previous working day.
Faster Payments and debit or corporate credit card payments are exceptions to that general weekend rule.
Who Needs to Submit a Self Assessment Tax Return?
Self Assessment is not required for everyone because tax for many employees and pensioners is collected automatically through PAYE.
A return is normally required where a person was self-employed as a sole trader and earned more than £1,000 before expenses, was a partner in a business partnership, had certain Capital Gains Tax obligations, or needs to pay the High Income Child Benefit Charge and is not paying it through PAYE.
A return may also be required for untaxed income from property, tips, commission, savings interest, dividends, foreign income or taxable UK income received by a non-UK resident.
Anyone who has been sent a notice requiring a tax return should deal with it even if they believe they no longer need Self Assessment.
They can contact HMRC about withdrawing the requirement where appropriate rather than simply ignoring the return.
What Happens If HMRC Gives You a Different Filing Deadline?
The standard 31 January 2027 deadline does not automatically apply when HMRC has formally provided another filing date.
A common example occurs when a person registers after 5 October 2026. HMRC can provide a deadline that is three months from the date of its letter or email.
This gives the taxpayer additional time to submit the return, but it does not necessarily provide additional time to pay.
For a 2025/26 tax liability, the normal payment deadline remains 31 January 2027. Someone registering late should therefore calculate and pay any tax due as quickly as possible rather than assuming their new filing deadline automatically postpones payment.
What Happens If You Miss the Tax Return Deadline?
Missing the filing deadline and missing the payment deadline are treated separately. A taxpayer could therefore submit their return on time but still face consequences if the tax is paid late.
Late Filing Penalties
Under the standard Self Assessment penalty system, the late filing charges can include:
- Initial Penalty: £100 after missing the filing deadline
- Three Months Late: £10 per day for up to 90 days, giving a maximum additional £900
- Six Months Late: 5% of the tax due or £300, whichever is greater
- Twelve Months Late: Another 5% of the tax due or £300, whichever is greater
The initial £100 penalty can apply even when there is no tax left to pay.
Late Payment Penalties and Interest
Tax paid late can generate a separate set of charges. Under the standard Self Assessment system, late payment penalties are generally 5% of the unpaid tax after 30 days, six months and twelve months.
Interest is also charged on overdue amounts.
Someone who realises they have missed the deadline should therefore file the outstanding return and pay as much of the tax as possible rather than waiting for HMRC to contact them.
What Should You Do If You Cannot Pay Your Tax Bill by the Deadline?
Being unable to pay does not remove the requirement to submit the tax return. Filing and payment are separate obligations, so the return should still be completed by the filing deadline wherever possible.
A taxpayer who cannot afford the full amount should contact HMRC as early as possible. Depending on their circumstances, HMRC may agree a Time to Pay arrangement that allows the debt to be cleared through instalments.
The amount someone can afford, their income, regular expenditure, other debts and the period required to clear the bill can all be relevant when an arrangement is considered.
Citizens Advice’s guidance on dealing with income tax arrears also explains that interest continues while Income Tax debt remains unpaid and that taxpayers seeking a payment arrangement should be ready to discuss their financial circumstances.
Ignoring the bill is generally more expensive than dealing with it early because interest and potential penalties can continue to build.
How Do Payments on Account Affect Your Tax Deadline?
Payments on account are advance payments towards the following year’s tax bill.
They are normally required unless the previous year’s relevant Self Assessment tax was less than £1,000, or more than 80% of the tax owed was already collected outside Self Assessment.
Each payment is normally half of the previous year’s relevant tax liability.
This means a taxpayer’s amount due on 31 January can sometimes be much larger than the balancing payment alone.
They may have to pay both their outstanding balance for the completed tax year and their first payment on account towards the next tax year.
For the current cycle, the usual schedule is:
31 January 2027: Balancing payment for 2025/26 plus the first payment on account for 2026/27.
31 July 2027: Second payment on account for 2026/27.
If income is expected to be lower, it may be possible to apply to reduce payments on account. However, reducing them too far can result in interest if the eventual tax liability is higher than expected.
Does Making Tax Digital Change Tax Return Deadlines From 2026?
Making Tax Digital for Income Tax began its mandatory rollout from 6 April 2026.
It initially applies to qualifying sole traders and landlords whose combined gross qualifying income from self-employment and property was more than £50,000 in 2024/25.
The qualifying threshold reduces to more than £30,000 from April 2027 and more than £20,000 from April 2028.
MTD does not simply remove the annual 31 January tax return deadline. Instead, affected taxpayers must keep digital records, send quarterly updates using compatible software and eventually submit their annual tax return through the MTD system.
For people using MTD from April 2026, the quarterly update deadlines for the 2026/27 tax year are 7 August 2026, 7 November 2026, 7 February 2027 and 7 May 2027.
The Self Assessment return covering 2025/26 is still due on 31 January 2027 using the usual process. The annual return covering the first full MTD tax year, 2026/27, will normally be due by 31 January 2028.
HMRC has also confirmed that penalty points will not be applied for late MTD quarterly updates during the first 2026/27 tax year.
Does Filing a Tax Return Affect Universal Credit Reporting?
Submitting a Self Assessment tax return does not replace the monthly reporting requirements for a self-employed Universal Credit claimant.
DWP requires self-employed claimants to report their business income and expenses for each Universal Credit assessment period.
This applies even where there was no business income or expense during that month and can apply even where DWP does not regard the person as gainfully self-employed.
The two systems serve different purposes.
Self Assessment reports taxable income to HMRC, usually on an annual basis. Universal Credit uses monthly income and expense information to help calculate benefit entitlement for individual assessment periods.
A claimant may therefore need to maintain records suitable for both systems. DWP states that records for Universal Credit and HMRC can be kept in a similar way, but the reporting periods and rules should not be treated as identical.
Reporting self-employed income late to Universal Credit can also delay a Universal Credit payment.
FAQs
Is the Self Assessment Deadline Always 31 January?
31 January is the standard deadline for most online Self Assessment returns, but exceptions exist. HMRC may provide a different deadline following late registration, and some specialist returns follow different rules.
What Tax Year Is Due on 31 January 2027?
The return due by 31 January 2027 normally covers the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026.
Can You File Online After Missing the Paper Deadline?
Yes. Someone who has not submitted their paper return by 31 October 2026 can generally switch to online filing and submit by the normal 31 January 2027 online deadline.
What Happens If You Miss the 5 October Registration Deadline?
Register as soon as possible. HMRC may give a filing deadline three months from the date of its letter or email, although tax for 2025/26 generally still needs to be paid by 31 January 2027.
Can HMRC Give You More Time to File?
HMRC can issue a different filing deadline in certain circumstances, particularly following late registration. A reasonable excuse may also be relevant when appealing a penalty, but taxpayers should not assume the normal deadline has automatically been extended.
Can You Submit Your Tax Return If You Cannot Pay the Bill?
Yes. The return should still be submitted by the filing deadline. Someone who cannot pay the full amount should deal with the payment problem separately and contact HMRC about available payment arrangements as early as possible.
