I completed my son's Illinois state tax for 2021 using Turbotax IL State Edition and filed in April.
As completed by Turbotax, for Step 1C (Personal Information) the box "You" is correctly checked because my son is claimed as a dependent on my return. In spite of this, Turbotax also included an exemption allowance of $2375 on line 10a.
The IL Dept of Revenue has sent a correction notice saying that because someone else can claim my son as a dependent, he cannot claim an exemption allowance, thus line 10a should be $0.
As far as I can discern, the State of Illinois is correct on this point, however I don't see a way to make that update in Turbotax. Even when I switch to Forms view in Turbotax, the value for line 10a is not editable.
Unless I am missing something, this appears to be a defect in Turbotax IL State Edition that it completed this value incorrectly, and does not allow me to manually override.
Does the notice from IL tell you to change your son's return and send in a corrected return----or did the state already make the correction for you? Are you sure you even need to do anything or do you just need to agree to the state's correction and leave it alone?
AUDIT SUPPORT
TurboTax has a special phone number for help with IRS/state tax letters, which will be easier than going through regular Customer Support. At the page below, click on the blue button that says "Get Help from TurboTax Support". Then it will ask you what tax year is your letter. Then it will ask you what the letter concerns. Then it will show you the phone number during posted business hours.
https://support.turbotax.intuit.com/irs-notice/audit-support/