Mont. Code Ann. § 15-31-311
15-31-311 Receipts factor for receipts in this state
15-31-311 . Receipts factor for receipts in this state. (1) Receipts from the sale of tangible personal property are in this state as provided for in Article IV, subsection (11), of 15-1-601 .
(2) Receipts, other than receipts provided for in subsection (1), are in this state as provided for in Article IV, subsection (12), of 15-1-601 .