Mont. Code Ann. § 15-7-403 — Rollback Tax -- Computation

15-7-403 . Rollback tax -- computation. (1) (a) Subject to 15-10-420 , if land and improvements appraised as residential as a result of an application filed under 15-7-402 are changed to industrial or commercial use, the property is subject to a rollback tax in addition to the property tax levied on the property. The rollback tax is a lien on the property and is due and payable by the owner of the property at the time of the change in use.
(b) As used in this section, "rollback" means the period preceding the change in use, not to exceed 5 years, during which the property was appraised as residential.
(2) The department shall determine the amount of rollback tax due on the property by:
(a) determining the taxable value of the property as industrial or commercial property;
(b) multiplying this value by the sum of the annual mill levies applied in the taxing jurisdiction in which the land is located during the rollback period; and
(c) subtracting from this figure the actual property tax paid on the property during this period.