IL HB1731

Increases the Illinois estate tax exclusion amount to $5,300,000 for persons dying on or after January 1, 2026, up from the current $4,000,000 threshold

Indexes the exclusion amount annually to inflation using the Consumer Price Index, with adjustments calculated based on the 12-month period ending September 30 of the preceding year

Allows surviving spouses to use their deceased spouse's unused Illinois estate tax exclusion (portability), mirroring the federal "deceased spousal unused exclusion" provision, for deaths on or after January 1, 2026

Modifies the State Death Tax Credit calculation so it applies only to the portion of a decedent's adjusted taxable estate that exceeds the exclusion amount

May be referred to as the "Estate Tax Inflation Law" and takes effect immediately upon becoming law