Mont. Code Ann. § 72-16-903
Taxable situs of property
72-16-903 . Taxable situs of property. For the purpose of the estate tax, the following have taxable situs in this state:
(1) real property located in this state;
(2) tangible personal property located in this state; and
(3) intangible personal property owned by a resident regardless of where it is located.