Q. Do I need to contact my company with this info and request a new W-2s for the last years, showing IL income?
A. No. It's your responsibility to pay the IL tax by filing an IL non resident return. You do not need a corrected W-2 from your employer to do so. But, it would be helpful, particularly with the OH amended returns.
Q. Or am I supposed to file IL, separately, in Turbo tax after I receive my W-2?
A. Yes. You can add the IL software to your TurboTax account.
You indicate you are paying City income tax for "the town where the company is located". If your employer is withholding city income tax on all your salary, for the year, you are actually entitled to a refund of the city tax paid on the salary allocated to IL (if you actually end up paying IL tax). This assumes you don't also live in the city where the company is located. This usually requires a special form from the city income tax dept.
School Tax does not work the same way. You owe school income tax on all your income, regardless of where you work, because you live in that school district.
