Self Assessment deadline: choose the right year.

Which dates apply to my return?

The current tax year is 2026/27, but the standard January 2027 deadline is for a 2025/26 return. Keep the income year separate from the date the return is sent.

The paper deadline is when HMRC receives the return. Online submission and payment are due by 11:59pm on the relevant date. The current-year dates follow the annual rule, subject to an HMRC notice and any later rule change. Source: filing and payment deadlines.

What if I missed the registration deadline?

Registration for the completed year was due by 5 October 2026. If you register later, HMRC states that the letter or email gives a filing deadline 3 months from its date. The payment date remains 31 January 2027. An extended filing date does not postpone payment. Read the late-registration rule.

Check how to register and keep the date in the HMRC notice rather than substituting the standard date.

What if the paper deadline has passed?

For 2025/26, the paper deadline was 31 October 2026. An eligible online return can use the later online deadline. A paper return received after its deadline can attract a late filing penalty even when no tax is due. Check permitted filing routes; see how penalties build up.

Do all taxpayers use the same timetable?

No. A notice issued after late registration can change the filing deadline. Trustees of a registered pension scheme, non-resident companies and some partnerships have specific filing rules. These are outside this individual guide. Read the deadline exceptions.

Payments on account may have a second due date in July; this is not a second tax-return deadline.