Diagnostic ref. #4552 states:
"IL-4562 may not calculate a special depreciation subtraction for luxury automobiles where limitations apply. Any subtraction should be calculated manually, and the newly calculated depreciation should be entered in the Special Depreciation Overrides section (Screen 51)." (ref. #4552)
Diagnostic ref. #12426 states:
"IL-4562 may not calculate a special depreciation subtraction for luxury automobiles where limitations apply. If bonus depreciation on a luxury auto exceeds the auto limit, no subtraction is allowed because no regular federal depreciation is allowed. In subsequent tax years, a subtraction will be allowed equal to the regular federal depreciation claimed on the auto even if that causes the total Illinois depreciation to exceed the auto limit." (ref. #12426)
What to do if you enter an override and the diagnostic doesn't clear
The diagnostic generates for an Illinois return when an asset is being depreciated with the auto limits applied. It's letting you know this issue may or may not apply to your clients' returns.
The diagnostic will remain in the Diagnostics tab, but won't prevent the electronic transmission of the return.