Any such person so transferring his membership shall notify the administrative head of the retirement system of which he is a member prior to or at the time of his withdrawal therefrom of his intention to enter the other retirement system. Such person shall retain all benefits earned in the system from which he is transferring and contributions made by a member to a retirement system as defined in § 8-3701, for retirement benefits shall not be refundable during any period such person is eligible for membership by transfer in any other system as set forth in this chapter.
T.C.A. § 8-3703