TTM01330 | Introduction to tonnage tax: Tonnage tax profits

Measurement of tonnage

Vessels of 24 metres in length or more

The gross or net tonnage of a vessel of 24 metres in length or more is measured in accordance with the IMO International Convention on Tonnage Measurement of Ships (1969). This International Convention came into force in 1984 and became mandatory for all vessels from 18 July 1994 (including both cargo and passenger vessels).

This tonnage will be recorded in an International Tonnage Certificate (1969).

If the vessel does not have a valid International Tonnage Certificate (1969) it will not be a qualifying ship.

Vessels of less than 24 metres in length

The gross or net tonnage a vessel of less than 24 metres in length is measured in accordance with:

• Regulations under section 19 of the Merchant Shipping Act 1995, or

• the legal provisions of a country outside the UK which correspond to those regulations.

This tonnage will be recorded in a certificate issued under the UK Regulations or their foreign equivalent.

It the vessel does not have a valid certificate recording its tonnage as measured in this way it will not be a qualifying ship.

Validity of certificates

It is not likely there will be any controversy about the tonnage of a ship, so it will not usually be necessary to request or examine the tonnage certificate.

If, exceptionally, there is doubt about the validity of a tonnage certificate refer to the Tonnage Tax Technical Adviser.

Further information on tonnage

Further information on tonnage and the different systems of measurement may be found in TTM15020.