Self-Assessment Tax Return Deadlines 2025/26 — Key Dates You Must Know

6 April — start of the new tax year.

5 October — register for Self Assessment if you need to file for the first time.

31 October — paper filing deadline (less common).

31 January — online filing deadline and balancing payment for the previous year.

31 July — second payment on account (if applicable).

QuickTaxFiler helps you complete Self Assessment and supplementary forms. If you have questions, use chat or email support@quicktaxfiler.co.uk.