SIOG1710 | Introduction and organisation: recording information: audit trail
From HM Revenue & Customs · Specialist Investigations Operational Guidance
All of the major decisions on a case - registration, agreeing profits, penalty loadings, and so on should be set out in writing and be readily identifiable and accessible. This is not a sign of weakness or ‘back covering’; it is vitally important in all cases. Even a number of years after a case has been settled, SI must be able to provide an audit trail of why and how the case was worked and concluded the way it was.