Wyo. Stat. § 35-9-627
Any member who has been a participating member for at least five (5) years may elect to make a one (1) time purchase of up to five (5) years of service credit as authorized and limited by section 415(c) and 415(n) of the Internal Revenue Code and as established in rules promulgated by the board. Any member electing to purchase service credit shall pay into the account a single lump sum amount equal to the actuarial equivalent of the benefits to be derived from the service credit computed on the basis of actuarial assumptions approved by the board, the individual's attained age and the benefit structure at the time of purchase. A member may purchase service credit with personal funds or, subject to rules and regulations established by the board, through rollover contributions. Unless received by the pension account in the form of a direct rollover, rollover contributions shall be paid to the pension account on or before sixty (60) days after the date the rollover contribution was received by the member.
W.S. 35-9-627