(a) The selection of any optional benefit pursuant to W.S. 9-3-420 shall be in writing, signed by both the member and any designated beneficiary and filed with the system prior to the first benefit payment.
(b) The election of an optional benefit is final and not subject to change unless a designated beneficiary dies prior to the first benefit payment. In such a case, the election is void, the member may designate a new beneficiary and may select a new option. Once the member receives a benefit payment, the option may not be changed for any reason including reemployment as a contributing member of the system or a second or subsequent retirement.
072-12 Wyo. Code R. § 12-6