# UK Self Assessment tax filing guidance

> Live situation record from CLSTR: https://clstr.news/situations/uk-self-assessment-tax-filing-guidance
> Updated: 2026-10-25T14:00:00.000Z. Sources: 4. Developments: 2.

HM Revenue and Customs (HMRC) is advising approximately 12 million Self Assessment customers to file their tax returns for the 2025 to 2026 tax year ahead of the 31 January 2027 deadline. Filing early is recommended to help taxpayers determine liabilities, manage budgeting, and receive refunds more quickly while avoiding penalties.

Late filings in the United Kingdom incur an automatic £100 penalty the day after the deadline. Additional penalties accrue at three, six, and twelve-month intervals, including daily penalties of £10 up to a maximum of £900 after three months, and further charges of 5% of the tax due or £300 at the six and twelve-month marks. 

Late payments are subject to separate penalties of 5% of the unpaid tax at 30 days, six months, and 12 months, in addition to interest charges. As of early 2026, the late payment interest rate was reported at 7.75%, calculated as the Bank of England base rate plus 4%.

## Timeline

### 2026-10-25: UK Self Assessment tax deadline approaches

HMRC is urging 12 million taxpayers to file Self Assessment returns before the 31 January 2027 deadline to avoid escalating penalties and interest charges.

2 sources. https://clstr.news/cluster/uk-self-assessment-tax-deadline-approaches

### 2026-10-23: HMRC urges UK taxpayers to file Self Assessment early

HMRC is urging 12 million UK taxpayers to file their 2025 to 2026 Self Assessment returns before the 31 January 2027 deadline to avoid penalties and manage budgeting.

3 sources. https://clstr.news/cluster/hmrc-urges-uk-taxpayers-to-file-self-assessment-early

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Cite as: UK Self Assessment tax filing guidance. CLSTR, https://clstr.news/situations/uk-self-assessment-tax-filing-guidance