If you are a sole proprietor use Schedule 1299-C Income Tax Subtractions and Credit.
If you are a Corporation filing IL-1120, Fiduciary filing IL-1040, or an Exempt Organization filing IL-990-T use Schedule 1299-D Income Tax Credits.
If you are a Partnership filing IL-1065 or an S corporation filing IL-1120-ST use Schedule 1299-A Tax Subtractions and Credits.