Mont. Code Ann. § 72-16-612

A personal representative acting in another state or a person required to pay the tax domiciled in another state may institute an action in the courts of this state and may recover a proportionate amount of the federal estate tax, of an estate tax payable to another state, or of a death duty due by a decedent's estate to another state from a person interested in the estate who is either domiciled in this state or who owns property in this state subject to attachment or execution. For the purposes of the action, the determination of apportionment by the court having jurisdiction of the administration of the decedent's estate in the other state is prima facie correct.