Idaho Code § 63-3013A: Part-year resident.

The term "part-year resident," for income tax purposes, means any individual who is not a resident and who:

(a) Has changed his domicile from Idaho or to Idaho during the taxable year; or

(b) Has resided in Idaho for more than one (1) day during the taxable year. An individual shall be deemed to reside within Idaho for any calendar day in which that individual has a place of abode in this state and is present in this state for more than a temporary or transitory purpose. Presence for any fraction of a calendar day shall be counted as a whole day.