In D S Sanderson v HMRC, the Court of Appeal confirmed that HMRC could make a discovery assessment under TMA 1970 s 29, even where details of the (pre-DOTAS) scheme were disclosed in the relevant return. In determining what HMRC could be reasonably expected to know, the courts have deemed the analysis to centre on a ‘hypothetical’ officer of general competence, knowledge or skill. In Sanderson, the court construed the bounds of relevant information narrowly. The case is the latest in a number of recent discovery cases in which the courts have attributed to the hypothetical officer very little knowledge, notwithstanding extensive information having been made available to HMRC.