EM2004 | Working the enquiry: reviewing earlier years: further profits for years subject to an earlier enquiry
From HM Revenue & Customs · Enquiry Manual
If your enquiry reveals further profits for a period which has already been adjusted in an earlier enquiry, you should normally seek a settlement to include penalties. This will be regardless of whether or not
penalties were taken in the previous enquiry
(This content has been withheld because of exemptions in the Freedom of Information Act 2000)
If a Certificate of Disclosure was signed on the earlier occasion and what you have now discovered throws its accuracy into doubt refer to EM3820.