You probably need to file an IL return. From the IL-1040 instructions, as an IL nonresident, you must file Form IL-1040 and Schedule NR if you earned enough IL 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.
Your exemption allowance would be less than the resident exemption allowance which is either $2,226 or $4,450 (depending on your filing status). So if your IL income is greater than this, you will need to file.
You should prepare your IL nonresident return first before your NY state resident return so that TurboTax can calculate the credit you will receive on your NY return for the IL tax.
Please see below the instructions for the IL-1040 and the IL-Schedule NR
You probably need to file an IL return. From the IL-1040 instructions, as an IL nonresident, you must file Form IL-1040 and Schedule NR if you earned enough IL 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.
Your exemption allowance would be less than the resident exemption allowance which is either $2,226 or $4,450 (depending on your filing status). So if your IL income is greater than this, you will need to file.
You should prepare your IL nonresident return first before your NY state resident return so that TurboTax can calculate the credit you will receive on your NY return for the IL tax.
Please see below the instructions for the IL-1040 and the IL-Schedule NR