Self Assessment: tax return for 2025/26 due by 31 January 2027

HM Revenue and Customs (HMRC) announced on 23 October 2026 that 100 days remain until the Self Assessment deadline. The return for the 2025/26 tax year must be filed, and any tax owed paid, by 31 January 2027.

Who is affected

HMRC expects around 12 million people to submit a tax return by 31 January 2027. It urges people not to leave it until the last minute. According to HMRC, filing early allows people to:

• find out how much tax they owe before the deadline,
• have more time to budget,
• get a refund sooner if they have overpaid,
• avoid penalties.

Myrtle Lloyd, HMRC's Chief Customer Officer, said now is a good time to file early.

How to file

Returns are filed online on GOV.UK. Anyone unsure whether they need to file can use the checker tool on the site. People new to Self Assessment must register first. They will then receive a Unique Taxpayer Reference (UTR), which is needed to file the return. Anyone who no longer needs to file returns can also tell HMRC on GOV.UK.

HMRC also points to available help: guidance on completing each section of the return, instructional videos and a digital assistant that answers common questions. People can also ask a tax agent, a friend, a family member or a voluntary organisation for help.

Key details

• People signed up to Making Tax Digital for Income Tax still file their Self Assessment return in the usual way and pay any tax owed by 31 January 2027.
• People with PAYE income who file online before 30 December can have tax owed collected through their tax code.
• The deadline for paper returns for 2025/26 is 31 October 2026.
• Anyone who received the 2025 Winter Fuel Payment and is in Self Assessment will see it pre-populated in the online return where possible, and should add it manually if it is not shown. Those with total income over £35,000 repay it through their tax bill.
• Around 300,000 people who pay the High Income Child Benefit Charge through Self Assessment will have Child Benefit details pre-populated in their online return.
• Gains on cryptoassets above the £3,000 tax-free allowance are subject to Capital Gains Tax and must be declared in the return.

What this means for you

The rules apply to everyone who has to file under Self Assessment, including people living in the UK who are self-employed or have income outside PAYE. If you are not sure whether you must file, check using the tool on GOV.UK. New filers need to register early to get a UTR.

HMRC also warns about fraudsters impersonating the department. Do not click links in unexpected messages or share your HMRC sign-in details.