Telling HMRC you need a Self Assessment return falls due on 5 October 2026

5 October 2026 is the deadline to tell HMRC you need to file a Self Assessment return for the 2025 to 2026 tax year. It applies to people who did not file a return last year.

This date is about registering, not filing. The return itself is due later, and missing the October date is a separate matter from missing the filing date. Registering is what lets HMRC issue the return in the first place, so it sits at the front of the Self Assessment year rather than the end.

First-time filers for 2025 to 2026

Newly self-employed people, new landlords, anyone with new untaxed income. A single new source of untaxed income in the tax year is enough to bring someone to this date.

Registering in time

• Work out whether you filed a Self Assessment return last year.
• Identify any income for 2025 to 2026 that has not been taxed at source.
• Tell HMRC you need to file, before 5 October 2026.
• Keep the registration confirmation with your tax records.
• If you did file last year, check whether HMRC still expects a return from you for 2025 to 2026.

Where the MTD ITSA system fits

Self Assessment for newly registered filers runs into Making Tax Digital for income tax, the nearest system in the register.

Verified 19 August 2026.

Back to every EU and UK compliance deadline left in 2026