IL SB3486

Eliminates the "80% foreign business activity" exclusion from unitary business groups for taxable years ending on or after January 1, 2026, requiring multinational corporations to include foreign affiliates in combined reporting for Illinois income tax purposes.

Removes certain exceptions that previously allowed deductions for interest and intangible expenses paid to foreign persons excluded from unitary groups, effective for tax years ending on or after December 31, 2025.

Expands the definition of "United States" for determining "foreign person" status to include the 50 states, District of Columbia, U.S. territories and possessions, and areas where the U.S. has asserted jurisdiction for natural resource exploration or exploitation.

Establishes joint and several liability for all members of a combined reporting group for tax obligations.

Takes effect immediately upon becoming law.