Synopsis As Introduced Creates the Historic Preservation Tax Credit Supplemental Pilot Program Act. Provides that an income tax credit is granted to an eligible taxpayer who makes expenditures pursuant to a qualified rehabilitation plan for the rehabilitation of a historic structure located in Rock Island County. Provides that the credit is available for taxable years beginning on or after January 1, 2019 and ending on or before December 31, 2029. Provides that the credit is equal to 25% of the amount of the eligible expenditure. Contains provisions concerning eligible expenditures. Provides that eligible taxpayers must apply with the Department of Commerce and Economic Opportunity within 6 months after the effective date of the Act. Provides that the credit may be carried forward for up to 10 years and may be carried back for up to 3 years. Amends the Illinois Income Tax Act to make conforming changes. Effective immediately.