Self Assessment deadlines: 2025/26 filing and 2026/27 income
Checked against official guidance: 26 October 2026.
Keep the year you earned income separate from the year you file. You may be filing 2025/26 while earning income in 2026/27.
| Income year | Normally register by | Paper return | Online return and payment |
|---|---|---|---|
| 2025/26 | 5 October 2026 | 31 October 2026 | 31 January 2027 |
| 2026/27 | 5 October 2027 | 31 October 2027 | 31 January 2028 |
Who needs to register?
If total relevant gross trading income is over £1,000, you normally need to tell HMRC. It is income before expenses, not profit. Other reasons can require a return even below £1,000, and a notice to file must be addressed. Use HMRC’s tax-return checker.
Missed 5 October 2026?
For 2025/26, register as soon as possible. HMRC says a late registration notice gives three months from the date of its letter or email to file. The tax payment deadline remains 31 January 2027. Do not assume the payment deadline moves with your filing deadline.
A dated example
You began trading in September 2025 and received £4,000 by 5 April 2026. If registration is required, the normal registration date was 5 October 2026; online filing and payment are normally due 31 January 2027. New work after 6 April 2026 belongs to the next tax year.
Prepare before filing
- Gross trading receipts across relevant activities.
- Allowable expense records or trading allowance eligibility.
- PAYE records such as your P60 and tax already deducted.
- Other taxable income and payments on account already made.
Submitting by 30 December 2026 may allow eligible 2025/26 tax to be collected through PAYE; check HMRC’s conditions. Payments on account can also fall on 31 January and 31 July.
Estimate 2025/26 tax · Estimate current-year tax · Understand advance payments
Source: HMRC Self Assessment deadlines.