State estate tax
Illinois estate tax in 2026
Checked against state sources 2026-10-21 · Gregory Garone, CEPA®
Short answer: Yes. Illinois taxes estates whose gross value, plus adjusted taxable gifts, exceeds $4 million. The $4 million is a threshold rather than a credit, so an estate just above it owes far more than a few dollars.
Illinois at a glance
| Tax type | Estate tax |
|---|---|
| Estate tax exemption, 2026 deaths | $4,000,000 |
| Top rate | 16% |
| Portability to a surviving spouse | No |
How the Illinois estate tax works
- The $4 million amount is not indexed for inflation.
- The Illinois Attorney General's examples show a $5 million estate owing about $285,714 in Illinois tax.
- Form 700 is filed with the Illinois Attorney General within nine months of death when the gross estate plus adjusted taxable gifts exceeds $4 million.
- Federal portability does not carry over to the Illinois calculation.
Planning points
- Couples with combined estates above $4 million usually need a credit-shelter or Illinois-specific QTIP trust to avoid wasting the first spouse's threshold.
- Because the tax rises steeply just above $4 million, lifetime gifts and charitable bequests that bring an estate under the line can save a disproportionate amount.
Common questions
Does Illinois have an estate tax in 2026?
Yes. Illinois taxes estates whose gross value, plus adjusted taxable gifts, exceeds $4 million. The $4 million is a threshold rather than a credit, so an estate just above it owes far more than a few dollars.
Is the Illinois $4 million exemption a credit?
No. The Attorney General describes it as a taxable threshold, not a credit, so the tax on an estate slightly over $4 million is calculated on more than just the excess.
Does Illinois allow portability between spouses?
No. A surviving spouse cannot use the unused Illinois exemption of a spouse who died first.
Sources and limitations
Other states
Planning around Illinois tax?
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