Article 5
1. As regards compulsory coverage, subject to the provisions of Articles 6 and 7, where a person who is insured under the legislation of one Party, and employed by an employer with a place of business in the territory of that Party, is sent by that employer, either from the territory of that Party, or from a third country, to work in the territory of the other Party, that person shall be subject only to the legislation of the former Party as if that person were working in the territory of that Party, provided that the period of such detachment is not expected to exceed five years.
2. As regards compulsory coverage, where a person insured under the legislation of one Party, who ordinarily works as a self-employed person in the territory of that Party, works only in the territory of the other Party, that person shall be subject only to the legislation of the former Party as if that person were working in the territory of that Party, provided that the period of the self-employment in the territory of the other Party is not expected to exceed five years.
3. Where, by virtue of the provisions of paragraph 1 or 2, a person works as an employed or self-employed person in the territory of one Party while remaining subject only to the legislation of the other Party, that person shall not be entitled to pay contributions voluntarily under the legislation of the former Party, unless such voluntary payments are made under the legislation of that former Party with respect to voluntary payment of contributions only by those aged sixty or over.
4. For the purpose of this Article, “insured” means,
(a)in relation to Japan, that, immediately before the commencement of the period of detachment or self-employment in the United Kingdom, contributions have been paid by, or in respect of, or are payable by, or in respect of, the person concerned, or exemption from liability for contributions has been granted to, or in respect of, the person concerned, and
(b)in relation to the United Kingdom, that, immediately before the commencement of the period of detachment or self-employment in Japan, contributions have been paid by, or in respect of, or are payable by, or in respect of, or have been credited in respect of, the person concerned.