Self Assessment deadline countdown: 31 January 2027
The deadline for filing your 2025/26 tax return online, and paying what you owe, is midnight on Sunday 31 January 2027.
Key dates for the 2025/26 tax return
| Date | What's due |
|---|---|
| 5 October 2026 | Register for Self Assessment if it's your first year (for example, a new sole trader or a new side income over £1,000) |
| 31 October 2026 | Paper tax return deadline |
| 30 December 2026 | File online by now if you want tax under £3,000 collected through your PAYE tax code |
| 31 January 2027 | Online return deadline, plus pay the balance for 2025/26 and your first payment on account for 2026/27 |
| 31 July 2027 | Second payment on account for 2026/27 |
Late penalties
- £100 as soon as the return is late, even if you owe nothing
- After 3 months, £10 a day for up to 90 days (up to £900)
- After 6 months, and again after 12 months, £300 or 5% of the tax due, whichever is higher
- Paying late: interest from 1 February, plus 5% late-payment penalties at 30 days, 6 months and 12 months
Checklist before you file
- Your UTR and Government Gateway login (activation codes are posted, so allow 10 days)
- P60 and P11D from any job, and pension and interest statements
- Self-employed: total income and expenses, mileage and use of home. See our sole trader expenses guide.
- Do you owe a High Income Child Benefit Charge?
- Work out your payments on account, so 31 January isn't a surprise
Source: GOV.UK Self Assessment deadlines, penalties. If you can't pay in full, you may be able to set up a Time to Pay plan online for debts up to £30,000.
Free calculator: Self-employed tax calculator: estimate the bill
Have every number ready for your tax return, sorted into HMRC's categories.
Income and expenses logs with HMRC categories, mileage, use of home, an estimate of income tax and Class 4 NI, and MTD-style quarterly totals.
Get it for £7 →All 9 paid templates (worth £48) for £15: about £1.67 each.
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Get it for £15 →FAQs
When is the Self Assessment deadline in 2027?
31 January 2027 for online returns for the 2025/26 tax year (6 April 2025 to 5 April 2026). Paper returns were due by 31 October 2026.
What happens if I miss the deadline by one day?
You get an automatic £100 penalty, even if you have no tax to pay. If you had a reasonable excuse, you can appeal.
Do I have to pay by 31 January too?
Yes. The balance for 2025/26 and any first payment on account for 2026/27 are both due by 31 January 2027.
Related calculators & guides
Personal tax account guide · Do I need a tax return? · Marriage Allowance · Take-home pay · Side hustle tax (£1,000 allowance) · Vinted & eBay HMRC check · Landlord tax guide · Payments on account
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