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HMRC internal manual

Tonnage Tax Manual

The 75% limit on charters-in: How to calculate 75% limit

All ships operated for whole accounting period

 It is the average percentage of chartered-in ships over the whole accounting period that is needed (FA00/SCH22/PARA37(5)).  Where all the company’s or group’s ships are operated for the whole of the accounting period, simply total the net tonnage of all vessels and compute the percentage of time and voyage charters in accordance with the table in Example 3 at TTM05240

Ships operated for varying periods during accounting period

Where there are varying periods of charter within the accounting period:

  • Find for each qualifying ship the number of days operated and her net tonnage.
  • Multiply the two figures to give the number of ton-days.
  • Add the total ton-days for the company’s/group’s qualifying ships.
  • Add the total ton-days of time and voyage charters-in.
  • Compute the percentage of time and voyage charters-in.

See Example 4 in TTM05250


For groups with the same or differing accounting periods see TTM05210.


FA00/SCH22/PARA37(5) (average percentage computed for AP) TTM17226