Exemption & rate verified against primary sources · Updated October 1, 2026
Illinois Estate Tax in 2026: Exemption, Rates & Calculator
Illinois has one of the most complex estate tax formulas of any state: instead of a simple bracket table, the tax owed is whichever is SMALLER of two different calculations tied to a decades-old federal credit table and a straightforward 40%-of-excess formula. The $4,000,000 exclusion hasn't moved since 2013.
Calculate Illinois estate tax for your situationHow Illinois taxes an estate
Illinois computes two numbers and charges whichever is lower: (a) a calculation based on the frozen pre-2001 federal 'state death tax credit' table, and (b) 40% of the amount by which the taxable estate exceeds $4,000,000, each adjusted for the fact that the tax itself reduces the taxable amount. Because of that interaction, there's no single flat 'Illinois rate' to quote — the effective rate actually declines as the estate grows past a certain point, which is why this page doesn't show a simple bracket table.
Worked example
A $10,000,000 Illinois taxable estate owes $926,923 — reverse-engineered from and verified exactly against the Illinois Attorney General's own official estate tax calculator. At $5,000,000, by contrast, the tax is $285,714 (also matching the Attorney General's own published example) — a smaller estate, but a HIGHER effective rate on the amount above the exclusion, because the 40%-of-excess formula controls at that lower level while the credit-table formula controls at $10,000,000.
Rules worth knowing
- Illinois's own Attorney General's office — which administers this tax — describes the calculation as "interrelated" and points practitioners to its own online calculator rather than a printed worksheet, because it genuinely isn't a simple lookup.
- The $4,000,000 exclusion has not increased since 2013 and is not indexed for inflation, unlike the federal exemption.
Filing deadline
The federal Form 706 return, when required, is due 9 months after the date of death (IRC §6075(a)). Illinois's own Form 700 has its own deadline — confirm the exact requirement with the Illinois Attorney General's office (which administers Illinois estate tax, not the Department of Revenue) rather than relying on the federal date.
How Illinois compares to the other states with an estate tax
13 states plus D.C. levy their own estate tax on top of the federal one, each with a different exemption, top rate, and calculation method — here's every one of them side by side.
| State | Exemption | Top rate | How it's calculated |
|---|---|---|---|
| Oregon | $1,000,000 | 16.0% | Graduated 10%–16% |
| Rhode Island | $1,838,056 | 16.0% | Federal credit table |
| Massachusetts | $2,000,000 | 16.0% | Federal credit table |
| Minnesota | $3,000,000 | 16.0% | Graduated 13%–16% |
| Washington | $3,000,000 | 20.0% | Flat 20% (date-sensitive) |
| Illinois (this page) | $4,000,000 | 16.0% | Lesser-of two formulas |
| the District of Columbia | $4,988,400 | 16.0% | Graduated 11.2%–16% |
| Maryland | $5,000,000 | 16.0% | Flat 16% (credit-table equiv.) |
| Vermont | $5,000,000 | 16.0% | Flat 16% |
| Hawaii | $5,490,000 | 20.0% | Graduated 10%–20% |
| Maine | $7,160,000 | 12.0% | Graduated 8%–12% |
| New York | $7,350,000 | 16.0% | Graduated + 105% cliff |
| Connecticut | $15,000,000 | 12.0% | Flat 12% |
Frequently asked questions
Does Illinois have an inheritance tax?
No. Illinois has an estate tax but no inheritance tax. The estate tax on this page is owed by the estate itself and paid before anything is distributed; beneficiaries do not owe a separate Illinois tax on what they receive. (Only Kentucky, Maryland, Nebraska, New Jersey, and Pennsylvania still charge an inheritance tax.)
What is the Illinois estate tax exemption in 2026?
$4,000,000 per person for deaths in 2026. Estates at or below that amount owe no Illinois estate tax. Illinois calls this the exclusion amount, and it is not indexed for inflation. The federal exemption is separate and much higher ($15,000,000 for 2026), so many estates owe Illinois estate tax and no federal estate tax.
What is the top Illinois estate tax rate?
16%. Illinois does not use a simple bracket table; the tax is the lesser of two formulas, which is why a rate you look up is only an approximation. See "How Illinois taxes an estate" above for how the rate is actually applied, and use the calculator for the exact figure on a given estate.
More on estate tax
For how federal estate tax interacts with Illinois's own rules, the 2026 federal exemption, and spousal portability, see the full estate tax guide.
How Illinois compares: for a single decedent dying in 2026, a $5,000,000 estate owes $285,714 in state estate tax in Illinois — 5th highest of the 7 jurisdictions that collect anything at that size, and a $10,000,000 estate owes $926,923. Federal estate tax is $0 in both cases. The full comparison across all 12 estate-tax states and DC, with a downloadable CSV, is in Inheritance and estate tax by state, 2026.