Self Assessment Deadline: 2026/27 Calendar

The main UK Self Assessment deadline is 31 January following the end of the relevant tax year. For the 2025/26 tax year, which ended on 5 April 2026, most taxpayers must submit their online return and pay the balancing amount due by 31 January 2027. Separate dates apply to registration, paper returns and payments on account.

The filing year can cause confusion because the tax return covers an earlier period. A return submitted in January 2027 normally reports income and gains received between 6 April 2025 and 5 April 2026. The 2026/27 tax year does not end until 5 April 2027, and its normal online filing deadline is 31 January 2028.

Self Assessment Deadlines for 2025/26

The following dates apply to most people completing a return for the year from 6 April 2025 to 5 April 2026. Registration, filing and payment are separate obligations. Meeting one deadline does not automatically satisfy the others.

According to the current HMRC Self Assessment deadlines, online returns for 2025/26 must normally be submitted by 11:59pm on 31 January 2027. Tax due for that return must also normally be paid by the same deadline. Filing the return does not automatically make the payment.

Self Assessment Registration Deadline

For a filing obligation arising in 2025/26, the normal registration deadline is 5 October 2026. This applies where you have not previously sent a return or were registered before but did not need to submit one for the previous year. HMRC’s current registration service also checks whether an existing Self Assessment account needs to be reactivated.

Registration is not the same as submitting the return. It establishes or reactivates the Self Assessment record and allows HMRC to provide the appropriate UTR and filing instructions. The guide explaining how to register as self employed covers the online process and existing-UTR cases.

If you register after 5 October 2026, HMRC says it will provide a filing deadline in its letter or email, normally three months from the date of that communication. However, tax for 2025/26 must generally still be paid by 31 January 2027 to avoid late-payment consequences. A failure-to-notify penalty may arise where registration is late and tax remains unpaid.

Paper and Online Tax Return Deadlines

HMRC must receive a paper return by the paper deadline. Posting it on 31 October does not guarantee that it has arrived on time. If the paper deadline has passed and the return can be submitted online, HMRC advises filing online by the January deadline to avoid a late-filing penalty.

The complete Self Assessment tax return guide explains the wider filing process, required records and return sections. This deadline hub does not repeat those completion instructions.

Deadline for Paying Through PAYE

For the 2025/26 return, the relevant filing date is 30 December 2026. This option can apply where less than £3,000 is owed, the taxpayer already pays tax through PAYE and HMRC’s other conditions are met. Filing by 30 December does not guarantee that coding will be available in every case.

If the return is submitted after 30 December, the online filing deadline remains 31 January 2027, but the taxpayer will normally need to pay using another accepted method. Check the calculation and HMRC account rather than assuming that the amount will automatically be collected through a tax code.

Self-Employed Tax Return Deadline

There is no separate national “tax day” exclusively for freelancers, contractors or sole traders. A self-employed person filing online for 2025/26 normally has until 11:59pm on 31 January 2027. The corresponding payment is generally due by the same deadline.

The obligation can still apply where the business stopped before the tax year ended. Income and expenses up to the cessation date may need to be reported in the final return. Taxpayers should also tell HMRC when Self Assessment is no longer required rather than simply stopping submissions.

Making Tax Digital for Income Tax changes how some sole traders and landlords keep records and submit information from April 2026. It does not remove the need to complete the relevant end-of-year tax return or final declaration by the applicable deadline. The MTD for Income Tax guide explains which taxpayers enter the digital system.

Self Assessment Payment Deadlines

The 31 January bill can contain more than one amount. For the 2025/26 return, it may include the balancing payment for 2025/26 and the first payment on account towards 2026/27. A second payment on account may then become due on 31 July 2027.

Not every taxpayer has to make payments on account. The requirement generally depends on the relevant previous-year liability and how much tax was collected outside Self Assessment. The dedicated payment on account deadline guide explains the £1,000 and 80% tests, calculations and permitted reductions.

Important 2026/27 Self Assessment Calendar

These are the standard dates for most individual returns. A different deadline can apply where HMRC issues a notice to file late, a trustee or partnership has specialist filing requirements, or another tax has its own reporting timetable. For example, some UK residential property gains must be reported and paid separately rather than waiting for the January Self Assessment deadline.

When Should You Submit Your Self Assessment?

The return for 2025/26 could be submitted from 6 April 2026. Filing early does not normally make the balancing payment due earlier, but it confirms the amount and provides more time to budget. It also leaves time to resolve missing records, access problems or calculation questions.

Do not file an incomplete return merely to finish early. Gather the relevant income, expense, pension, property and investment records before submission. Review the calculation and keep the submission confirmation after HMRC accepts the return.

After processing, the taxpayer may need an SA302 tax calculation or account evidence. The SA302 form guide and Tax Year Overview example explain how those documents differ and when they become available.

What Happens If You Miss the Deadline?

According to HMRC’s current penalty guidance, the initial late-filing penalty is £100. It can apply even where no tax is due. If the return remains outstanding, additional daily and tax-related penalties can follow.

Late payment is separate. HMRC’s established rules provide for penalties of 5% of qualifying unpaid tax at 30 days, six months and 12 months, with interest charged separately. The precise result can depend on the taxpayer, liability and applicable penalty regime.

Submit and pay as soon as possible rather than waiting for HMRC to issue a penalty. The guide to the late tax return penalty where no tax is due covers the full timeline, reasonable-excuse appeals and the distinction between filing and payment penalties.

How to Meet the Deadline

1. Confirm whether a return is required.
2. Register or reactivate Self Assessment before 5 October where applicable.
3. Check that the UTR and online account are accessible.
4. Collect income, expense and tax-deduction records.
5. Submit the return after checking every reported source.
6. Save the submission confirmation and final calculation.
7. Check the balancing payment and any payments on account separately.
8. Use the correct HMRC payment reference and allow enough processing time.

Government Gateway access problems do not automatically move the statutory deadline. Test the account well before January and use official HMRC support if identity verification or service access fails. Keep evidence of significant service problems and attempts to resolve them.

Common Deadline Mistakes

The return filed by 31 January 2027 covers 2025/26, not income earned during January 2027 alone. Another common error is assuming that a submitted return automatically takes payment. Filing and payment must be checked separately in the HMRC account.

Taxpayers also overlook the earlier 31 October paper deadline or miss the 30 December PAYE-coding date. Others pay the balancing amount but fail to notice the first payment on account included in the January bill. Reading the calculation and statement line by line helps keep these amounts separate.

Finally, do not assume that receiving no reminder removes the obligation. The taxpayer remains responsible for meeting the applicable date. Calendar reminders and early filing provide more protection than relying on January correspondence.

This guide provides general information about UK Self Assessment deadlines for 2025/26 and 2026/27. Different deadlines can apply in specialist circumstances, and HMRC rules or digital services may change. Check your HMRC account and GOV.UK for the dates applying to your return. For personalised advice, consult a qualified tax adviser or contact HMRC directly.