22 U.S.C. § 3983: Assignments to non-Service and other positions

in a non-Foreign Service (including Senior Executive Service) position in the Department or another agency, or with an international organization, international commission, or other international body; with a domestic or international trade, labor, agricultural, scientific, or other conference, congress, or gathering; for special instruction, training, or orientation at or with a public or private organization; and in the United States (or in any territory or possession of the United States or in the Commonwealth of Puerto Rico), with a State or local government, a public or private nonprofit organization (including an educational institution), or a Member or office of the Congress. The salary of a member of the Service assigned under this section shall be the higher of the salary which that member would receive but for the assignment under this section or the salary of the position to which that member is assigned. The salary of a member of the Service assigned under this section shall be paid from appropriations made available for the payment of salaries and expenses of the Service. Such appropriations may be reimbursed for all or any part of the costs of salaries and other benefits for members assigned under this section. A member of the Service assigned under subsection (a)(4) to a Member or office of the Congress shall be deemed to be an employee of the House of Representatives or the Senate, as the case may be, for purposes of payment of travel and other expenses. Except as otherwise provided in subsection (d)(5), assignments under this section may not exceed four years of continuous service for any member of the Service unless the Secretary approves an extension of such period for that member because of special circumstances. The Secretary may assign a member of the Service, or otherwise detail an employee of the Department, for duty at the American Institute in Taiwan, if the Secretary determines that to do so is in the national interest of the United States. The head of any other department or agency of the United States may, with the concurrence of the Secretary, detail an employee of that department or agency to the American Institute in Taiwan, if the Secretary determines that to do so is in the national interest of the United States. a noncareer appointee, limited term appointee, or limited emergency appointee (as such terms are defined in section 3132(a) of title 5 ) in the Senior Executive Service; or an employee in a position that has been excepted from the competitive service by reason of its confidential, policy-determining, policy-making, or policy-advocating character. An assignment or detail under this subsection may be made with or without reimbursement from the American Institute in Taiwan. The period of an assignment or detail under this subsection shall not exceed a total of 6 years, except that the Secretary (or any other head of a department or agency of the United States, with the concurrence of the Secretary) may extend the period of an assignment or detail for an additional period of not more than 6 years.