Here are Illinois' filing requirements for non-residents (see the Note regarding trust income):
- a nonresident, you must file Form IL-1040 and Schedule NR if
- you earned enough taxable income from Illinois sources to have a tax liability ( i.e., your Illinois base income from Schedule NR, Step 5, Line 46, is greater than your Illinois exemption allowance on Schedule NR, Step 5, Line 50), or
- you want a refund of any Illinois Income Tax withheld in error. You must attach a letter of explanation from your employer.
NOTE: If you are a nonresident and your only income in Illinois is from one or more partnerships, S corporations, or trusts that withheld enough Illinois Income Tax to pay your liability, you are not required to file a Form IL-1040.
https://www2.illinois.gov/rev/individuals/filingrequirements/Pages/default.aspx
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
