(a)  Any active teacher who served on active duty in the armed service of the United States or in the merchant marine service of the United States as defined in § 2 of Chapter 1721 of the Public Laws, 1946, may purchase credit for that service up to a maximum of four (4) years; provided that he or she has received an honorable discharge; provided further, that any teacher on an official leave of absence for illness or injury shall be eligible to purchase military credits as defined herein while on that leave of absence.

(b)  The cost to purchase these credits shall be ten percent (10%) of the member‘s first year’s earnings as a teacher as defined in § 16-16-1 of this title, multiplied by the number of years and fraction of the years of the armed service up to a maximum of four (4) years.

(c)  There will be no interest charged provided the teacher makes that purchase during his or her first five (5) years of membership in the retirement system, but will be charged regular interest to date of purchase from date of enrollment into membership, if purchased after completing five (5) years of membership; provided, however, any teacher who was in the retirement system prior to July 1, 1980, would not be charged interest whenever he or she purchases the armed services credit.