If you made contributions to a pretax deferred compensation plan, those are reported on your W-2 and are automatically not taxed as they are deducted from your the box 1 income, which should be equal to the income reported in box 16 of the W-2 for your Illinois wages.
If you received a 1099-R for distributions, enter that as normal in TurboTax. TurboTax will automatically remove that income from your Illinois taxable income on line 5 or your IL-1040 return. If using TurboTax download version, you can view your IL-1040 form by clicking on Forms at the top right, then look for your IL-1040 return in the left column and click on it to double check that the subtraction has been made.
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