The principle that a dependent child takes the domicile of their parent applies only to minor children. Since you are 22 years old, you would consider Illinois as your State of Residence for all of 2024 if you began living in Illinois prior to 01/01/2024 with the intent (as evidenced by your actions) of making Illinois your new domicile. See Section L, "Meaning of Domicile" on page 10 of this California tax publication:
https://www.ftb.ca.gov/forms/2023/2023-1031-publication.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
