What is the deadline for submitting a self-assessment tax return in the UK?

In the UK, the deadline for submitting a self-assessment tax return is 31 January following the end of the tax year. This means for the tax year that runs from 6 April to 5 April of the next year, individuals are required to submit their self-assessment by the following 31 January.

This timeline is crucial for taxpayers as it allows them sufficient time to prepare their financial information for the preceding tax year while ensuring the tax authorities can manage and process assessments efficiently.

The other options reflect incorrect dates that could lead to confusion. For instance, December 31 would not provide adequate time for individuals to compile their financial records post-tax year-end. Similarly, March 31 and June 30 fall outside of the acceptable submission period as they are either too early or too late, missing the January deadline established by HM Revenue and Customs (HMRC). Hence, option B accurately represents the proper deadline for filing self-assessment returns in the UK.