From what I see, IL does not tax active duty military pay. But since you are a part-year resident of IL for 2018 I'm not exactly clear. As I understand it, your military pay is included in your state AGI,probably for the purpose of determining your tax bracket on any taxable non-miliary pay. But the military pay is not taxed. Take a look at http://www.revenue.state.il.us/Publications/Pubs/Pub-102.pdf and see if you understand it the same as I do.
