My son, was on an internship in Florida from 1/2022 to 6/2022. His state of residence was Illinois. He took a full time job in Florida right after the internship. Florida does not have state income tax but I think he would have to file as a part year resident for Illinois. He has an apartment in Florida, car registration and drivers license. Does that sound accurate that he would have to file as part year resident for Illinois? Any help would be appreciated. Thanks