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

HMRC internal manual

Tonnage Tax Manual

Offshore activities pre 2005: Types of vessel

Vessels to which the special rules apply

The special rules apply to all qualifying ships (TTM03500) engaged in offshore activities (TTM11010), unless they are of a type which is specifically excluded (see below).


  • a vessel is time-chartered out to a service provider on long-term charter, and
  • during the term of the charter the charterer utilises the vessel on the United Kingdom Sector of the Continental Shelf (UKCS),

the fact that the owner has no control over the vessel’s area of operations does not prevent the special rules from taking effect.

But the special rules will not be applied unless a company’s ships are engaged in offshore activities for more than a total of 30 days in any accounting period (TTM11140).

Examples of vessels to which the special rules apply are:

  • diving support vessels
  • heavy lift crane barges
  • seismic survey ships
  • safety standby ships

This list is not exhaustive. See TTM11120 for how to deal with multi-purpose vessels, which can both carry out specialist offshore activities (e.g. safety standby) and act as a type of vessel exempted from the offshore regime (e.g. supply vessel).


FA00/SCH22/PARA103(2) (number of days do not exceed 30) TTM17591
Different types of vessel and their treatment TTM11100
Vessels to which special rules do not apply TTM11120
De minimis activity ignored TTM11140