Illinois and Iowa have tax reciprocity with regard to W-2 wages and salaries.
That means that, if you as an Iowa resident worked in Illinois, and your earnings were reported to you on a W-2, you would only have to file an Iowa tax return. Such earnings are not taxable by Illinois. They are taxable only by Iowa.
The only exception would be if your employer mistakenly withheld Illinois taxes. In that case, you'd have to file a non-resident Illinois return, showing zero Illinois income, in order to have those taxes refunded to you.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
