This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Company Taxation Manual

Corporation tax self-assessment (CTSA): Claims and elections: Fraud or neglect

FA98/SCH18/PARA65 (1) and (2) provide that, when you make an assessment on a company as a result of fraudulent or negligent conduct it can make additional claims.

The only claims it can make are those that can be given effect in that assessment. They must therefore be made before you issue the assessment or in the appeal period.