Amends the Property Tax Code. Provides that, beginning in taxable year 2024, no taxing district, other than a home rule unit, may levy a tax on any parcel of real property that is more than 105% of the base amount unless (i) the increase is attributable to substantial improvements to the property, (ii) the taxing district did not levy a tax against the property in the previous taxable year, or (iii) the increase is attributable to a special service area. Provides that "base amount" means the tax levied by the taxing district on the subject property in the immediately preceding taxable year, except that, if the property received a homestead exemption in the immediately preceding taxable year and is not eligible for that exemption in the current taxable year, then the base amount shall be the tax that would have been levied by the taxing district on the subject property in the immediately preceding taxable year if the homestead exemption had not been applied. Provides that a taxing district may elect to be exempt from those provisions for one or more taxable years if the exemption is approved by referendum. Effective immediately.