Summary of the issues reviewed by the Illinois Supreme Court in Irwin Industrial Tool Co. v. Department of Revenue.

The legal question was whether the Illinois Department of Revenue can impose a use tax on the full value of an aircraft even though it is hangared outside of the state of Illinois.

The Supreme Court concluded that Illinois’ use tax based on the full purchase price of the airplane is externally consistent and thus fairly apportioned because no tax has been paid on the airplane to any other state, and even if it had been, the Use Tax Act provides an exemption for sales or use taxes paid to other states.

The Court affirmed the appellate court reversal of that portion of the circuit court’s judgment limiting the use tax to 4% of the airplane’s purchase price.