22 U.S.C. § 4052: Mandatory retirement

Except as provided in subsection (b), any participant shall be retired from the Service at the end of the month in which the participant has reached age 65 and has at least 5 years of service credit toward retirement under the System (excluding military and naval service), and shall receive retirement benefits in accordance with section 4046 of this title . an individual described in section 4(a)(2) of the Department of State Special Agents Retirement Act of 1998 who is otherwise eligible for immediate retirement under this subchapter; or a Foreign Service criminal investigator/inspector of the Office of Inspector General of the Agency for International Development who would have been eligible for retirement pursuant to either section 8336(c) or 8412(d)(1) of title 5, as applicable, had the employee remained in civil service, Any participant who is otherwise required to retire under subsection (a) while occupying a position to which he or she was appointed by the President, by and with the advice and consent of the Senate, may continue to serve until that appointment is terminated. Whenever the Secretary determines it to be in the public interest, any participant who is otherwise required to retire under subsection (a) may be retained on active service for a period not to exceed 5 years. Any participant who completes a period of service authorized by this subsection shall be retired at the end of the month in which such authorized service is completed.