Creates the Local Option School District Income Tax Act and amends the School Code, the State Finance Act, the Illinois Income Tax Act, and the Property Tax Code. Authorizes school districts by referendum to impose an income tax on individuals resident of the district. Provides that the income tax must be levied at a rate that will produce an amount equal to the corresponding 50% reduction in property taxes for educational, operations and maintenance, and transportation purposes. Provides for a referendum repeal of the tax. Sets forth procedures for levying and collecting the tax and for deposit of the income tax revenues. Provides for disbursement of the tax to school districts by the State Treasurer. Amends the Property Tax Extension Limitation Law to exclude from the definition of “aggregate extension” school district levies made to cover amounts lost because of the repeal of the local income tax for schools as formerly imposed by the district under the Local Option School District Income Tax Act. Amends the State aid formula provisions of the School Code. Provides that the adoption or failure to adopt a local income tax for schools and any disbursement of funds or any tax abatement required under the Local Option School District Income Tax Act shall not affect the computation or distribution of State aid for school districts. Effective immediately.