Tax Return Deadline 2025 Uk. You must tell hmrc by 5 october 2025 if you need to complete a tax return and have not sent one before. This date holds immense significance for taxpayers across the united kingdom.

31 october 2025 (midnight) deadline for online submission of self assessment tax returns for year ending 5 april 2023 for hmrc to collect employment or pension income tax. However we recommend registering as soon as you can.