An IL resident paid 100k for deducible alimony , receives an IL W- 2 and receives a CO K-1 for 75,000 and paid CO taxes of 3,300.   When calculating the IL CR schedule, IL adds back the alimony and the apportionment becomes 0.0000, be cause the income from Column B is -25,000.

Why does IL force the taxpayer to add back the deducible alimony?