053-17 Wyo. Code R. § 17-11
(a) A member of an Employer Group who has been authorized to withdraw from such an Employer Group, or upon notification that the Employer Group has been authorized to be dissolved, may continue on a reimbursable election or may elect to become a tax based employer beginning January 1 of the year succeeding the effective date of withdrawal or dissolution provided that the employer makes written application with the Division at least thirty (30) days prior to the effective date of the employer's withdrawal or the dissolution of the Employer Group, whichever may be the case. The election to become a tax based employer as of January 1 of the calendar year succeeding the withdrawal from or the dissolution of the Employer Group on December 31 of the prior year, must remain in effect for at least two (2) calendar years.
(b) Such an employer who, by election, changes from the reimbursable method to a tax base method of financing benefit costs, must reimburse the Wyoming Unemployment Compensation Fund for his proportionate share of benefits paid to his former employees who are in a claim status and the base period earnings of such claimants which were earned during the period that the employer was reporting under the reimbursable method of financing benefit costs as a member of an Employer Group. Such an employer, in addition to making payment of any reimbursable amount which might be due to the Division, is required to file contribution reports quarterly as a tax base employer.
053-17 Wyo. Code R. § 17-11