Illinois Estate Tax Calculator: the facts

1. Illinois taxes estates above $4,000,000. The federal estate tax begins at $15,000,000 for deaths in 2026. Between those two lines, Illinois is the only estate tax that applies.
2. A $5,000,000 all-Illinois estate owes the state $285,714 and the federal government $0. That is the state's own published example.
3. Just over the line, each added dollar costs about 28.6 cents of Illinois tax. The ramp eases at about $5.4 million, where the state's credit schedule takes over.
4. Illinois lets a surviving spouse inherit none of a late spouse's unused exclusion. A married couple with $7,000,000 owes Illinois $565,603 at the second death if everything passed outright to the survivor, and $0 if the first death set $4,000,000 aside.
5. For an Illinois decedent with one federal exclusion, the federal tax stays at $0 until the estate reaches about $16.9 million, because the Illinois tax is deducted before the federal tax is figured.
6. Property sited outside Illinois shrinks the bill in proportion. A $5,000,000 estate with half its property in Florida owes $142,857, half the all-Illinois figure, even though Florida has no estate tax.
7. SB 3847 would raise the line to $8,000,000 for deaths from January 1, 2027. As of September 3, 2026: Referred to Senate Assignments on February 6, 2026; a co-sponsor was added June 26, 2026. It has not passed either chamber and is not law.

Educational only, not investment, tax, or legal advice. Results are hypothetical estimates that vary with each use and over time and are not guaranteed accurate or complete. Using this tool creates no client relationship with Considerate Capital, and the site that linked here is not affiliated with it. By using it you agree to the tool terms (opens in a new window).