(1) The taxable classification of all qualifying new industrial property becomes effective beginning on the first assessment date on or after the initial commencement date of operations.

(2) The new industrial property taxable classification runs for three consecutive years after commencement of operations. This period runs to its expiration date uninterrupted by additions of property to the new industry endeavor, expansion of operations, changes of operations (other than changes that would disqualify the new industry endeavor from classification as new industrial property) or cessation or curtailment of operations.

(3) Prior to and after the three-year period of classification as new industry property, the property in question is taxable as other similar property.

(4) For all property other than migratory personal property, the taxable year is considered to be the calendar year. The assessment date within any given calendar year is January 1.

(5) For migratory personal property that enters Montana after the regular assessment date and comes to rest and becomes a part of the general property within any county of the state, the assessment date is the date the property originally entered the state. This property shall be taxed from the time it enters the state until the end of the year. For purposes of assessment year proration on this migratory personal property, any part of a month is considered a month of residency.