Updated October 7, 2026. Quick answer: Illinois’ estate tax exclusion is $4,000,000 for deaths in 2026, and nothing in the Attorney General’s current documents changes it for 2027: they print $4,000,000 for deaths on or after January 1, 2023 and give no indexing rule or 2027 figure. The federal exclusion is $15,000,000 for 2026.
Illinois estate tax exemption: 2026 and 2027 at a glance
| Item | What the documents say |
|---|---|
| Exemption, 2026 deaths | $4,000,000 |
| How it is set | A taxable threshold, not a credit |
| 2027 figure | No 2027 figure or indexing rule in the Attorney General’s documents; they print $4,000,000 |
| Rates | No schedule printed; the Attorney General’s calculator computes the tax |
| Return and deadline | Form 700, due nine months after death |
| Federal basic exclusion amount, 2026 | $15,000,000 |
| Sources | Illinois Attorney General; IRS Revenue Procedure 2025-32 |
What changes in 2027
The Attorney General’s fact sheet states that the exclusion amount for Illinois estate tax purposes is $4,000,000, and Form 700, the return for decedents dying on or after January 1, 2023, prints the same $4,000,000.
Neither document gives a 2027 amount or says the figure adjusts for inflation, so the best reading is that $4,000,000 continues. That is a reading of silence, not an announcement: the Attorney General has not posted a 2027 notice in the documents read.
How the Illinois estate tax works
The fact sheet says the exclusion is a threshold, not a credit. It works an example in which a $4,000,000 estate owes $0 and a $5,000,000 estate owes $285,714. The tax comes from an interrelated calculation, so the Attorney General offers an online calculator; CMG’s page on it is the Illinois estate tax calculator.
The tax is due nine months after the date of death. On carrying over an unused federal exemption, the fact sheet says portability does not apply to the Illinois computation.
In the documents’ own words
- Important Notice Regarding Illinois Estate Tax and Fact Sheet (Illinois Attorney General): “exclusion amount is a taxable threshold and not a credit”
- State of Illinois Estate & Generation-Skipping Transfer Tax Return, Form 700 (Illinois Attorney General): “FOR DECEDENTS DYING ON OR AFTER JANUARY 1, 2023”
How this compares with the federal exemption
Federal estate tax is separate. Revenue Procedure 2025-32 says the One Big Beautiful Bill Act, section 70106, increased the “basic exclusion amount to $15,000,000 for calendar year 2026”. CMG’s page on the federal exemption for 2027 is the federal estate tax exemption for 2027. The state figure on this page is not the federal one: it is the amount at which Illinois starts to tax an estate.
What the documents do not say
- The statute (35 ILCS 405) could not be read when this page was built, so the indexing rule is the Attorney General’s silence, not a statutory statement.
- No rate schedule is printed in the two documents read.
Common mistakes
- Treating $4,000,000 as a credit; the Attorney General says it is a taxable threshold.
- Assuming the federal portability election carries into Illinois.
Related: Illinois estate tax (2026), estate tax by state, the federal estate tax exemption for 2027, Illinois probate cost, and Illinois retirement taxes.
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Answer againSources
- Important Notice Regarding Illinois Estate Tax and Fact Sheet: https://illinoisattorneygeneral.gov/Page-Attachments/EstateTaxInstructionFactSheet.pdf
- State of Illinois Estate & Generation-Skipping Transfer Tax Return, Form 700: https://illinoisattorneygeneral.gov/Page-Attachments/form700.pdf
- Revenue Procedure 2025-32 (Internal Revenue Service): https://www.irs.gov/pub/irs-drop/rp-25-32.pdf
Sources: the primary documents linked above, read on October 7, 2026. General information, not tax advice. Your own facts decide the outcome, and an estate attorney, a tax preparer or the state agency itself is the right place to confirm anything consequential.