UT (Tax & Chancery) UT-2024-000024 - [2025] UKUT 00156 (TCC)

A closure notice takes effect when it is issued.”

Where HMRC have opened an enquiry, they are free to ask for all relevant information and will come to a decision as to whether the amount of tax self-assessed in the return is right or wrong. When they have come to a decision they issue a closure notice under paragraph 23, which the taxpayer can appeal against under paragraph 35.

If HMRC do not open an enquiry within the permitted period they can only challenge the amount of tax declared in the return by raising an assessment under paragraph 28 ("a discovery assessment"). We return to the law governing discovery assessments when considering the Assessment Appeal below.