Article 4 is intended to eliminate dual coverage, the situation that occurs when a worker is covered under the laws of both countries with respect to the same services. In so doing, the Agreement preserves the existing coverage provisions of the laws of both countries to the greatest extent possible. The provisions in this Article are intended to eliminate dual coverage by continuing the worker's coverage and taxation under the system of the country to whose economy he or she has the more direct connection and exempting the worker from coverage and taxation under the other country's system.

Article 4.1 establishes a general rule for eliminating dual coverage and contributions for persons working in either the United States or Japan. Article 4.2 contains an exception to this general rule, which applies in the case of employees sent by an employer in one country to work temporarily in the other country. Article 4.4 provides for the elimination of dual coverage in the case of self‑employed persons who move temporarily from one country to the other. Articles 4.5 and 4.6 preclude dual coverage that might otherwise occur for employees in international shipping and air transportation. Article 4.7 establishes rules applicable to persons employed in U.S. or Japanese Government service.