105 ILCS 5/24-13.1
By mutual agreement of a teacher and the employing board, the board may, but is not required to, grant the teacher a leave of absence to accept employment in a Department of Defense overseas dependents' school. If such a leave of absence is granted, the teacher may elect, for a period not exceeding the lesser of the period for which he is so employed or 5 years, (a) to preserve his contractual continued service status under this Act, and (b) to continue receipt, on the same basis as if he were teaching in the school system subject to the employing board, of service credit earned for requirements of promotion, incremental increases in salary, leaves of absence and other privileges based on an established period of service or employment. In addition, a teacher whose armed forces reserve unit is activated during the school year and who as a result is required to enter into active military service duty shall continue to have his or her full salary as a teacher paid by the school board for the first 2 weeks of the period during which he or she is required to remain on active military service duty; provided, however, that if the teacher is required to remain on active military service duty for any additional period, his or her contractual continued service under this Act shall be preserved, and he or she shall continue to receive throughout the entire period that he or she is required to remain on active military service duty, on the same basis as if he or she were teaching in the school system governed by the employing board, service credit earned for requirements of promotion, incremental increases in salary, leaves of absence and other privileges based on an established period of service or employment; provided further that a teacher who receives payment of his or her full salary as a teacher for the first 2 weeks of the period his or her armed forces reserve unit is required to remain on active military service duty shall return to the school board such portion of his or her teaching salary so paid as is equal to the payment he or she received for such 2 week period from his or her armed forces reserve unit, excluding, however, all payments received by the teacher from the armed forces reserve unit which are allocable to nonschool days or which constitute a travel, meal or housing allowance.
A person employed to replace a teacher making the election provided for in this Section does not acquire contractual continued service status as a teacher under this Article.
105 ILCS 5/24-13.1