The EU protocol relates both to the Isle of Man and to the Channel Islands.
Read Protocol 3 in full below:
The Community rules on customs matters and quantitative restrictions, in particular those of the Act of Accession, shall apply to the Channel Islands and the Isle of Man under the same conditions as they apply to the United Kingdom. In particular, customs duties and charges having equivalent effect between those territories and the Community, as originally constituted and between those territories and the new Member States, shall be progressively reduced in accordance with the timetable laid down in Articles 32 and 36 of the Act of Accession.
The Common Customs Tariff and the ECSC unified tariff shall be progressively applied in accordance with the timetable laid down in Articles 39 and 59 of the Act of Accession, and account being taken of Articles 109, 110 and 119 of that Act. 2. In respect of agricultural products and products processed therefrom which are the subject of a special trade regime, the levies and other import measures laid down in Community rules and applicable by the United Kingdom shall be applied to third countries. Such provisions of Community rules, in particular those of the Act of Accession, as are necessary to allow free movement and observance of normal conditions of competition in trade in these products shall also be applicable.
The Council, acting by a qualified majority on a proposal from the Commission, shall determine the conditions under which the provisions referred to in the preceding sub-paragraphs shall be applicable to these territories.
The rights enjoyed by Channel Islanders or Manxmen in the United Kingdom shall not be affected by the Act of Accession. However, such persons shall not benefit from Community provisions relating to the free movement of persons and services.
The provision of the Euratom Treaty applicable to persons or undertakings within the meaning of Article 196 of that Treaty shall apply to those persons or undertakings when they are established in the aforementioned territories.
The authorities of these territories shall apply the same treatment to all natural and legal persons of the Community.
If, during the application of the arrangements defined in this Protocol, difficulties appear on either side in relations between the Community and these territories, the Commission shall without delay propose to the Council such safeguard measures as it believes necessary, specifying their terms and conditions of application. The Council shall act by a qualified majority within one month.
In this Protocol, Channel Islanders or Manxmen shall mean any citizen of the United Kingdom and Colonies who holds that citizenship by virtue of the fact that he, a parent or grandparent was born, adopted, naturalised or registered in the Island in question; but such a person shall not for this purpose be regarded as a Channel Islander or Manxman if he, a parent or a grandparent was born, adopted or naturalised or registered in the United Kingdom. Nor shall he be so regarded if he has at any time been ordinarily resident in the United Kingdom for five years. The administrative arrangements necessary to identify these persons will be notified to the Commission.
The Effect of the Protocol
Under the above Protocol, the Isle of Man is part of the customs territory of the Union. It follows that the Common Customs Tariff, levies and other agricultural import measures apply to trade between the Isle of Man and non-member countries and that there is free movement of goods in trade between the Isle of Man and the Union as regards industrial and agricultural products. However, subject to compliance by the Isle of Man authorities with the principle of equal treatment for all natural and legal persons in the Union, the other Union rules do not apply.
The provisions of the European Union Treaties on the free movement of persons, services and capital and the provisions concerning the common policies, in particular, eligibility for assistance from the structural funds and the support measures for agricultural markets do not therefore apply to the Isle of Man.