42 CFR § 406.25 - Special enrollment period for volunteers outside the United States.
(a) General rule. A SEP, as defined in § 406.24(a)(4) of this subchapter, is provided for an individual that meets the following requirements:
(1) The individual is serving as a volunteer outside of the United States in a program that covers at least a 12-month period.
(2) The individual is in a program that is sponsored by an organization described in section 501(c)(3) of the Internal Revenue Code of 1986 and is exempt from taxation under section 501(a) of Internal Revenue Code of 1986.
(3) The individual can demonstrate that he or she has health insurance that covers medical services that the individual receives outside the United States while serving in the program.
(4) The individual -
(i) At the time he or she first met the requirements of § 406.10 through 406.15 or § 406.20(b), elected not to enroll in premium hospital insurance during the individual's initial enrollment period; or
(ii) Terminated enrollment in premium hospital insurance during a month in which the individual met the requirements of this section for a SEP.
(b) Duration of SEP. The SEP is the 6-month period beginning on the first day of the month that includes the date that the individual no longer meets the requirements of paragraph (a) of this section.
(c) Effective date of coverage. Coverage under a SEP authorized by this section begins on the first day of the month following the month in which the individual enrolls.