31st January 2024 - Online Tax Return Deadline and Payment Deadline.
This date is the most important deadline for self-assessment tax returns. If you're filing your tax return online for the year 2022-2023, it must be submitted to HMRC by midnight on 31st January 2024.
You'll also need to pay any tax you owe by this date, including the first instalment of any payments on account for the 2023-2024 tax year and any balancing payments owed from 2022-2023.
