Amends the Property Tax Extension Limitation Law in the Property Tax Code. Provides that, for levy years 2022 and later, the taxing district's aggregate extension base is the greater of (A) the district's last preceding aggregate extension limit or (B) the district's last preceding aggregate extension, subject to certain adjustments. Provides that the term "aggregate extension limit" means the district's last preceding aggregate extension if the taxing district had utilized the maximum limiting rate permitted without referendum for each of the 5 immediately preceding levy years. Provides that the maximum reduction under the General Homestead Exemption is $10,000 in counties with 3,000,000 or more inhabitants, $8,000 in counties that are contiguous to a county of 3,000,000 or more inhabitants and $6,000 in all other counties. Provides that the maximum reduction under the senior citizens homestead exemption is $8,000 in counties with 3,000,000 or more inhabitants and counties that are contiguous to a county of 3,000,000 or more inhabitants and $5,000 in all other counties (currently, $8,000 in counties with 3,000,000 or more inhabitants and $5,000 in all other counties). In provisions concerning the homestead exemption for veterans with disabilities, makes changes concerning the surviving spouse. Provides that the interest rate under the Senior Citizens Real Estate Tax Deferral Act is reduced from 6% to 4%. Amends the School Code. Contains provisions concerning interfund transfers and disclosure of cash reserve balances. Amends the Department of Revenue Law of the Civil Administrative Code of Illinois to require the Department of Revenue to conduct a study concerning the homestead exemption for veterans with disabilities. Effective immediately.