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HMRC internal manual

Company Taxation Manual

Corporation Tax self-assessment (CTSA): Assessments: Discovery - when prohibited

You cannot make a discovery assessment if the company:

  • has made a return for the relevant period and you can pursue the discovery by opening an enquiry into the return, or
  • has received a notice requiring it to deliver a return, and it has not made a return for the relevant period, and you are still in time to make a revenue determination for that period (see CTM95300 onwards).