I retract my earlier comment. Turbotax is right, at least for me. On page 9 of the IL-1040 instructions, there is an income exception:
"Income Exceptions
If your federal filing status is married filing jointly and your federal AGI is greater than $500,000, you are not entitled to a property tax credit or a K-12 education expense credit.
If your federal filing status is single, head of household, married filing separately, or widowed and your federal AGI is greater than $250,000, you are not entitled to a property tax credit or a K-12 education expense credit.
"
Even though I couldn't find any documentation on the above in Turbotax, Turbotax's math is correct. I just e-filed.
