For Illinois, go to the Estimated Tax Worksheet. (Go to View>Forms>Illinois Individual>Estimated Wks). Part II of the worksheet is Overpayment Application Options. Line 2 in Part II allows you to enter the amount of your 2023 overpayment that you want applied to your 2024 Estimated Tax.
Alternatively: Proceed through the Illinois online "interview" until you get to the page headed "A few things before we wrap up your state taxes". Then click on "Estimate Taxes for next year" and proceed through the follow-up questions.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
