INTM596530 | Arbitrage: legislation and principles: procedures: Discovery notices
From HM Revenue & Customs · International Manual
Once the period in which an enquiry into a return may be made has elapsed or an enquiry has been closed, HM Revenue and Customs may issue a notice only if either:
the absence of a notice was due to fraudulent or negligent conduct on the part of the person to whom the notice is issued, a person acting on their behalf, or their partner; or
the Commissioners of HM Revenue and Customs could not have been reasonably expected to realise that a notice should have been issued on the basis of information supplied before the enquiry period had lapsed.
In the above circumstances, the Commissioners of HM Revenue and Customs may issue a notice and also a discovery assessment to give effect to the notice. The notice may be varied until the discovery assessment becomes final.