Self Assessment Tax Return Tax Year 2025 Tax Year. Hmrc must have received your tax. You have until 11.59pm on wednesday 31 january 2025 to send hmrc an online tax return for the 2023/2024 tax year, which ended on 5 april 2024.

Want to know the dates for 2023/24? A single definition of tax year to replace the current practice of assessment year and financial year;