CH122140 | Offshore matters: asset-based penalties: definitions: offshore matter
From HM Revenue & Customs · Compliance Handbook
An offshore matter is an inaccuracy or failure that leads to a potential loss of revenue that is charged on or by reference to:
income arising from a source in a territory outside the UK
assets situated or held in a territory outside the UK
activities carried on wholly or mainly in a territory outside the UK
anything having effect as if it were income, assets or activities of a kind described above.
For further information on offshore matters in relation to the following penalties see below: