Can anyone tell me where I can put a part of my 2023 Illinois state refund and credit a portion of it on my 2024 Illinois return? Using 2023 online software

To apply part of your overpayment from your 2023 tax return to your 2024 tax return, you will need to make the entries in the state interview section.

1. Log back into TurboTax and select State Taxes.
2. Select Continue to the right of Illinois.
3. Proceed through the screens until you see the screen titled "Your 2023 Illinois taxes are ready for us to check." Scroll down and select edit to the right of Other situations.
4. On the screen titled "A few things before we wrap up your state taxes," scroll down and select the down arrow to the right of Other forms.
5. Select start to the right of Estimate tax payments for next year.
6. On the screen titled, "do you want to pay Illinois Estimated Taxes for 2024," select yes.
7. Proceed through the screens and answer the questions as applicable until you see the screen titled Apply Overpayment.
8. On this screen, you can select Apply Specific Amount and select Continue.
9. The next screen will ask you for the amount to apply.  Enter the amount you want to apply towards your 2024 Illinois state tax return.