Under Article 4.2, an employee working for an employer located in the United States or the United Kingdom who is temporarily transferred to work in the other country for the same employer (including its parent corporation or a foreign subsidiary of the same employer) will continue to be covered by the country in which the employer is located.  Ordinarily this rule will apply only if the period of work in the other country does not exceed 5 years.   Provision has been made for extending the 5-year limit if the Competent Authorities agree to a requested extension.  If a person’s employment is not covered in the country in which his or her employer is located, this paragraph does not apply and the person is generally subject to the laws of the country in which he or she is working.  Article 4.2 will apply even if the employee is not sent directly to the other country but is first assigned to work in a third country.  This paragraph does not apply to employment in international air or ship transportation, which is dealt with in Article 4.5.  The Supplementary Agreement amended Article 4.2 to make clear that, in order for the 5-year temporary exemption from a host country’s social security system to apply, the employee who is being transferred must normally have been working for the sending employer in the territory of the first country immediately before being sent to the other country.  This change was intended to prevent application of the rule in situations where the employee does not have a current connection to the labor market in the first country.  For example, the rule would generally not apply to a person who has been working outside the United States and not covered under U.S. Social Security, and who is brought briefly to the United States to sign an employment contract with a U.S. employer before being temporarily transferred to the United Kingdom.  In this case, Article 4.2 would not apply since the individual did not have a current connection to the U.S. economy; rather, the territoriality rule in Article 4.1 would apply so that the worker would be subject only to U.K. law.