HCOS4325 - Post detection audit and assessment: periods of assessment
You should attempt to establish when the misuse started. This may be apparent from the records or may have been established during the interview. Look in the records for evidence of when purchases of rebated oil began or purchases of unrebated diesel decreased or stopped. If records are not available, RIS Operations Compliance Excise (ROCE) or a local Registered Dealer in Controlled Oil (RDCO) should be able to provide information on supplies of rebated oil to the offender.
Assessments of excise duty can be made for a period of up to three years, or up to 20 years in cases involving fraud (civil evasion or criminal cases).