IL SB3540

Caps annual assessed value increases on residential property to the prior year's assessed value plus the Consumer Price Index percentage change from the preceding 12-month calendar year, beginning with the 2026 assessment year

Exempts properties from the assessment cap when value increases result from additions, improvements, modifications, or sale of the property

Applies statewide to all counties in Illinois, preempting home rule units' authority to set different property tax assessment standards

Amends the Property Tax Code (35 ILCS 200/9-145) while maintaining the existing 33 1/3% fair cash value assessment standard for property valuation