If you take the Standard Deduction in the Federal Return, you will not enter your property tax on the Federal Return. Once you get to the State Return, it will display two boxes, one to enter the "Property taxes paid" and one for "Amount not on principal residence". For most people, the second box ("not on principal residence") will be zero. You can continue on just fine and TurboTax will tell you the amount of the credit and everything seems fine.
The problem is when TurboTax runs the review of the IL State Return, it will flag this as "Needs Review".
However, if you go back into the Fed Return and try to enter your property tax, it will put up a screen saying, "We don't need this. You took the Standard Deduction." You can continue past that screen and enter your property tax info.
When you go back to the Property Taxes page on the IL Return, it prompts you with two DIFFERENT boxes, "Property taxes NOT on residence" and "Property taxes deductible elsewhere". Put zeros in those boxes and it completes the State Return review process without any issues.
It looks like there is a bug in the State Review code that looks at these numbers and flags them as a problem. I guess the workaround is to just ignore it.
