IL HB1791

Establishes a standardized property tax assessment method for commercial energy storage systems in Illinois counties with fewer than 3,000,000 inhabitants, effective for assessment years 2025 through 2040

Sets the real property cost basis at $124 per kilowatt hour of rated energy capacity, with fair cash value calculated by subtracting physical depreciation (based on a 15-year depreciation schedule) from the trended cost basis adjusted for inflation using the Consumer Price Index

Exempts commercial energy storage systems from equalization factors applied by the Department of Revenue, boards of review, assessors, or chief county assessment officers

Requires commercial energy storage system owners to commission and pay for a metes and bounds survey of the property, with the chief county assessment officer issuing a separate parcel identification number for tax assessment purposes

Allows land previously assessed as farmland to return to farmland assessment status after removal of a commercial energy storage system, and permits taxing districts to abate property taxes on these systems by majority vote