Wyo. Stat. § 2-10-108
Neither the fiduciary nor other person required to pay the tax shall be under any duty to institute any suit or proceeding to recover from any person interested in the estate the amount of the tax apportioned to the person until the expiration of the three (3) months next following final determination of the tax. A fiduciary or other person required to pay the tax who institutes the suit or proceeding within a reasonable time after the three (3) months period shall not be subject to any liability or surcharge because any portion of the tax apportioned to any person interested in the estate was collectible at a time following the death of the decedent but thereafter became uncollectible. If the fiduciary or other person required to pay the tax cannot collect from any person interested in the estate the amount of the tax apportioned to the person, the amount not recoverable shall be equitably apportioned among the other persons interested in the estate who are subject to apportionment.
W.S. 2-10-108