Amends the Property Tax Code. Provides that, in all counties, any change in assessment resulting from reassessment in the general assessment year shall not exceed the lesser of the following: (1) 3% of the assessed value of the property for the prior year; or (2) the percentage change in the Consumer Price Index during the 12-month calendar year preceding the assessment year. Provides that the limitation does not apply if the increase in assessment is attributable to an addition, improvement, or modification to the property. Preempts the power of home rule units to tax. Effective immediately.