A detached worker is an employee who is sent by the employer in one country to work temporarily in the other country for the same employer or an overseas affiliate of the same employer. Under the agreement, a detached worker remains subject only to the social security laws of the country from which the worker was sent, provided the following conditions are met:

1. 1. 

   The employment relationship must exist before the employee is transferred from the home country, although the transfer need not be directly from the home country to the host country but may be via a third country.

2. 2. 

   The employment in the host country must be expected to last no longer than 5 years. The 5-year period is considered to begin with the date the employment in the host country begins or the effective date of the agreement, whichever is later.

3. 3. 

   In the case of a worker who is sent by an employer in the United States to work for an affiliate of that employer in Spain, the American employer must have entered into an agreement under section 3121(l) of the Internal Revenue Code (see RS 01901.070) with respect to the Spanish affiliate.

Ordinarily, the detached worker rule will apply only if the temporary assignment in the host country is expected to last for not longer than 5 years. However, if during the assignment, the expectation changes and the total duration of the worker's stay in the host country will exceed 5 years, the agreement provides that the employer may, with the consent of the worker, request that the detached worker rule continue to apply for up to 1 additional year. Any such request must be made before the expiration of the original 5-year period, and should be addressed to the appropriate agency in the home country (see RS 02001.485). Neither country will grant an extension unless the other country concurs in the request. If an extension is not requested, or a requested extension is denied, the employee's coverage will switch to the host country's social security system and the employee will be exempt from home country coverage.

The agreement provides that, in general, the categories of government workers mentioned in the Vienna Conventions on diplomatic and consular relations will not be affected by the coverage provisions of the agreement. The Conventions, to which both Spain and the U.S. are parties, apply to members of the staff of a diplomatic or consular mission, including the diplomatic, consular, administrative, and technical staffs; dependents of members of those staffs; the domestic service staff of the missions; and, under certain conditions, the private servants employed by members of such missions.

In general, nationals of a country who work abroad in the diplomatic or consular service of their country are exempt under the Conventions from social security coverage and contributions under the laws of the host country unless specific arrangements have been made to waive their exemption. Persons who waive their exemption under the Conventions are subject to the coverage provisions of the agreement.

Under the terms of the agreement, a U.S. or Spanish national who is employed by the Government in the other country but who is not exempt from host country coverage by virtue of the Vienna Conventions is nevertheless subject only to the laws of the employee's own country.

Under the agreement, a member of the flight crew of an aircraft operating between the United States and Spain who would otherwise be covered under the laws of both countries will be covered only under the laws of the country in which the airline company has its headquarters. However, if the employee resides in the other country, the employee will be covered instead under the laws of that country.

The agreement provides that a person employed on a U.S. or Spanish ship who would otherwise be covered under the laws of both countries will be covered only under the laws of the country whose flag the ship flies. A ship is considered to fly the flag of the U.S. if it is an American vessel as defined in section 210(c) of the Social Security Act (see RS 01901.150).