35 ILCS 110/3-60
The tax imposed by this Act does not apply to the use, in this State, of property that is acquired outside this State by a nonresident individual who then brings the property to this State for use here and who has used the property outside this State for at least 3 months before bringing the property to this State.
Where a business that is not operated in Illinois, but is operated in another state, is moved to Illinois or opens up an office, plant, or other business facility in Illinois, that business shall not be taxed on its use, in Illinois, of used property that the business bought outside Illinois and used outside Illinois in the operation of the business for at least 3 months before moving the used property to Illinois for use in this State.
35 ILCS 110/3-60