Horsehead Corp. v. Department of Revenue, 2019 IL 124155

Horsehead Corporation purchased metallurgical coke out-of-state and used it in a Waelz kiln at its Calumet City, Illinois zinc-refining facility to reduce electric arc furnace (EAF) dust and recover zinc and iron.
The Illinois Department of Revenue assessed use tax, interest, and late-filing/late-payment penalties for 2007–2011 because Horsehead had not paid Illinois use tax on those coke purchases.
Horsehead claimed the coke was exempt under the Use Tax Act §3-50(4) (the “chemical exemption”) because the coke purportedly effected a “direct and immediate change” on the products being manufactured.
Evidence showed coke is consumed in the kiln to produce carbon monoxide, and it is the carbon monoxide (not solid coke) that reduces zinc oxide and iron oxide during the multi-step Waelz process.
The Illinois Independent Tax Tribunal and the appellate court upheld the tax liability, denied the exemption, and affirmed penalties; the Illinois Supreme Court affirmed the tax liability but reversed the penalties determination.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether coke qualifies for the §3-50(4) chemical exemption (must "effect a direct and immediate change")	Horsehead: coke effects a direct and immediate change on zinc/iron in the manufacturing process and thus is exempt	Department: coke acts only indirectly (via intermediate production of CO) and therefore does not produce a direct and immediate change	Court: held coke does not effect a direct and immediate change; exemption denied; tribunal not clearly erroneous
Standard of review for Tax Tribunal’s statutory interpretation and mixed questions	Horsehead: de novo review because tribunal lacks rulemaking/enforcement power	Department: tribunal is a tax-expert administrative body; mixed questions get tribunal deference	Court: tribunal has tax expertise; legal questions de novo, mixed questions reviewed for clear error; applied clearly erroneous standard here
Whether late-filing and late-payment penalties should be abated for reasonable cause	Horsehead: ambiguity in the statutory phrase and lack of controlling caselaw made its position reasonable; thus penalties should be abated	Department: taxpayer failed to produce evidence showing reliance or reasonable cause; penalties appropriate	Court: reversed tribunal on penalties — decision to impose penalties was against manifest weight; abatement warranted

Performance Marketing Ass’n v. Hamer, 2013 IL 114496 (explains purpose of use tax and preventing sales tax avoidance)
Provena Covenant Medical Center v. Department of Revenue, 236 Ill. 2d 368 (tax exemptions construed narrowly; burden on claimant)
Van’s Material Co. v. Department of Revenue, 131 Ill. 2d 196 (doubts about exemption resolved for taxation)
Elementary School District 159 v. Schiller, 221 Ill. 2d 130 (standard of review: legal questions de novo; mixed questions clearly erroneous)
AFM Messenger Service, Inc. v. Department of Employment Security, 198 Ill. 2d 380 (framework for mixed question review)
Comprehensive Community Solutions, Inc. v. Rockford School District No. 205, 216 Ill. 2d 455 (statutory interpretation and deference principles)
Abrahamson v. Illinois Department of Professional Regulation, 153 Ill. 2d 76 (review standard and weight of evidence considerations)
Hollinger International, Inc. v. Bower, 363 Ill. App. 3d 313 (reasonable-cause factual determination for penalty abatement)