IL SB1543

Creates a new Illinois state income tax deduction for union dues paid by taxpayers beginning January 1, 2026, when those dues were not deductible on the federal return due to the 2% floor on miscellaneous itemized deductions under IRC Section 67

Allows the full amount of union dues to be deducted from Illinois base income if no federal deduction was permitted; if a partial federal deduction was allowed, the Illinois deduction is reduced proportionally

Defines union dues as amounts deductible under IRC Section 162 as union dues and agency shop fees

Exempts this deduction from the Illinois Income Tax Act's automatic sunset provision, making it permanent

Amends Section 203 of the Illinois Income Tax Act (35 ILCS 5/203) to add the new deduction as subparagraph (NN) under individual income modifications