On November 15, 2021, President Biden signed into law the Infrastructure Investment and Jobs Act (IIJA), Public Law 117-58, 135 Stat. 429. Section 80201 of the IIJA reinstates the Superfund excise tax on certain chemical substances under Sections 4661 and 4671 of the Internal Revenue Code (Tax Code), effective July 1, 2022. Section 80201(c)(1) of the IIJA modified the method for determining whether a substance is a taxable substance by lowering the required percentage of taxable chemicals used to produce the substance from 50 percent to 20 percent of the weight (or the value) of the materials used to produce such substance. Since its reinstatement, the excise tax has raised many questions and caused significant industry consternation. This memorandum explains why. For more information, please read the full memorandum.