IL SB1817

Defines "mid-range ethanol blend" as a gasoline and denatured ethanol blend containing not less than 20% but less than 51% denatured ethanol.

Imposes tax on mid-range ethanol blends at 80% of proceeds for sales from July 1, 2019 through December 31, 2023, then 100% of proceeds thereafter.

Modifies definition of "gasohol" to allow the maximum proportion of ethanol authorized by the EPA under the Clean Air Act, rather than a fixed 10% requirement.

Changes "majority blended ethanol fuel" definition to require 51-83% ethanol (per ASTM Standard D5798-11) and capability for use in flexible fuel vehicles.

Applies the same mid-range ethanol blend tax treatment across the Use Tax Act, Service Use Tax Act, Service Occupation Tax Act, and Retailers' Occupation Tax Act; effective immediately.