Someone tells you the Illinois estate tax rate is 16%. You think about what you have, say $4,700,000, and you do the sum in your head: $752,000 less for your children.
That is not the tax. If that $4,700,000 is your taxable estate, all of it in Illinois, the state's own computation comes to $200,000.3 The 16% is real, but it is only the top row of an old federal table the state still uses. No estate pays 16% of its value to Illinois. Every row of that table is in the detailed version at the foot of this page.
What is the Illinois estate tax rate?
There is no single rate you can apply. Illinois charges nothing until your taxable estate, together with the large taxable gifts you made during your life, is over $4,000,000.1 Your taxable estate is what you own at death, less your debts, and less the amounts going to your spouse or to charity that the tax rules let you subtract.2 Above $4,000,000, what your estate owes depends on its whole size.
What is the effective Illinois estate tax rate at $5, $6, $8 and $10 million?
The effective rate is the tax divided by the whole taxable estate. It tells you how much of everything you leave would go to Illinois and not to the people you named.
The share rises with the estate, but slowly. If your estate doubled from $5,000,000 to $10,000,000, the part of it going to Illinois would move from 5.7% to 9.3%.
How does the tax add up above $4,000,000?
The more you have, the more Illinois takes, both in dollars and as a share of the estate. It is easiest to see in three parts.
That is where the $200,000 at the top of this page comes from: $700,000 over the line, at about 28.6 cents on the dollar. It is also why the share keeps rising: the first $4,000,000 is a smaller piece of a larger estate.
The middle part is the one to notice. It adds the most for each dollar, and the households in it are often the ones that never planned for an estate tax, because they did not think they had enough to owe one. A paid-off house, two retirement accounts, and a life insurance policy can be enough to get there.
The tax does not begin with a jump. One dollar over the line costs about 29 cents, not hundreds of thousands.3
The tax does not begin with a jump. One dollar over the line costs about 29 cents, not hundreds of thousands.
How much is the inheritance tax in Illinois?
Nothing. Illinois has no inheritance tax, so your children do not each get an Illinois bill on what they inherit. What people call the Illinois inheritance tax, or the death tax, is the estate tax on this page: one tax, figured on the estate as a whole and paid by the estate.4
What are the Illinois estate tax brackets?
If someone has shown you a list of Illinois estate tax brackets that ends at 16%, this is the table they were reading. Illinois has no bracket table of its own. It uses a federal table for state death taxes as it stood on December 31, 2001, with 20 rows and rates from 0.8% to 16%.5 You cannot read your tax off it the way you read your income tax bracket. The state adjusts the estate before it finds your row, and one of the things it subtracts is the tax itself. That is one reason no estate pays 16%.
Neither you nor the person who settles your estate has to do this by hand. The Attorney General publishes a calculator that does the arithmetic.1 The whole table is in the detailed version below, and the steps are in how the Illinois estate tax is calculated.
What is the rate on your own estate?
Type your taxable estate into our Illinois estate tax calculator. It runs the same computation the state publishes and shows the Illinois tax with the federal tax beside it.
Refine for gifts already made, property outside Illinois, or the proposed law
Enter the gifts that were reported on a federal gift tax return, and leave them out of the estate above. Illinois counts them toward its exclusion but figures its table on the estate alone.
- Illinois estate tax
- $456,071
- Federal estate tax
- $0
- Both taxes combined
- $456,0717.6% of the estate
Illinois is the only estate tax that applies at this size. The estate is over the Illinois exclusion but under the federal one.
This is a simplified model, not your actual tax return or plan. It only knows what you type in, leaves out rules that may apply to you, and cannot weigh the other facts and trade-offs a real decision depends on. Before you act, talk with a professional who knows your whole situation.
Under 2026 law, reviewed November 10, 2026. One taxable estate after deductions; nothing to a spouse or charity. Full methodology and sources.
The figures on this page are for one person whose estate is entirely Illinois property, with no taxable gifts and nothing passing to a spouse or to charity. Yours can differ. If you are married and everything passes to your husband or wife, the first of you usually owes Illinois nothing, and the tax usually comes due at the second death.1 If you own real estate in another state, Illinois charges only its share of the tax.4 The federal estate tax is separate, and in 2026 it starts above $15,000,000 for one person who has made no large taxable gifts.7 And the $4,000,000 line itself may change. A bill in Springfield would raise it to $8,000,000 for deaths on or after January 1, 2027. When we last checked, on November 10, 2026, it had not passed either chamber and is not law.6
What the rate is and what to do about it are two different questions. Our Illinois estate tax guide covers who owes the tax and how married couples are treated, and the planning essay covers the tools for reducing it. Which of them fit your estate is a decision for your estate attorney and your CPA.
Where we fit in. We integrate tax considerations into your investment strategy and collaborate with estate attorneys and CPAs to ensure your plan is coordinated. We are not a law firm or accounting firm, so we do not provide legal or tax advice. Everything in this material is for educational purposes, based on primary sources. Before taking any action, please consult the appropriate professionals to apply these ideas to your situation.
The number that matters was never the 16%. It is the amount that reaches the people you are leaving it to. If you would like to go through your own figures with someone, we are glad to have that conversation.
The detailed versionThe full rate scheduleFor CPAs, estate attorneys, and anyone who wants every row: the statute, the 2001 table, marginal and effective rates by estate size, and what changes them.Show
Statutory basis
The Illinois Estate and Generation-Skipping Transfer Tax Act states no rate of its own. Under 35 ILCS 405/3 the tax equals the "state tax credit."4 35 ILCS 405/2 defines that credit as the full credit calculable under Internal Revenue Code § 2011 as that section stood on December 31, 2001, without the later reduction or termination of the credit, recognizing an exclusion amount of only $4,000,000 for persons dying on or after January 1, 2013.8 The Illinois rates are therefore those of the § 2011(b) table as of that date, limited under § 2011(e) by the § 2001 tax after the unified credit.5
The § 2011(b) table as of December 31, 2001
From table rate to marginal rate
E is the Illinois tentative taxable estate with every asset treated as Illinois property. G is adjusted taxable gifts.
The table is applied to E less $60,000 less the Illinois tax.3 A dollar added to E therefore adds r ÷ (1 + r) of tax, where r is the rate of the row in use. The 16% row yields 0.16 ÷ 1.16, or 13.79%.
A second computation starts with E + G, subtracts the tax, and limits the tax to 40% of what is left over $4,000,000.3 The 40% is the § 2001(c) rate on amounts over $1,000,000.9 The limit solves to (E + G − 4,000,000) ÷ 3.5, a marginal rate of 28.57%.
The tax is the lesser of the two. With no adjusted taxable gifts, the limit gives the lower tax from $4,000,000 to $5,359,167, and the table governs above that.
The formula for the tax in each range, and a worked example at $5,000,000, are in the full calculation.
Effective rates
As E grows, the tax as a share of the estate gets closer to 13.79% and stays below it. Measured against only the amount over $4,000,000, the tax is 28.6% through the limit range. It then falls toward 13.79% and stays above it. The exclusion amount is "a taxable threshold and not a credit against tax."1
What changes the rate
- Adjusted taxable gifts count toward the $4,000,000 line and enter the 40% limit only. In the Attorney General's published example, an estate of $3,000,100 with $1,000,000 of adjusted taxable gifts owes $28.1
- Property outside Illinois. The tax is computed as if every asset were in Illinois and then multiplied by the Illinois share of the gross estate.4 In the published example, a $5,000,000 estate with half its property in Florida owes $142,857, which is 2.86% of the estate.1
- An Illinois marital (QTIP) election, made on a timely filed Illinois return, reduces the Illinois base.8 In the published example, $13,610,000 less an election of $9,610,000 leaves $4,000,000, and the tax is $0.1
- Deductions. The rates apply to the taxable estate, which is the gross estate less the deductions allowed by the Internal Revenue Code.2
"Inheritance tax rate"
The Act imposes an estate tax "on every taxable transfer involving transferred property having a tax situs within the State of Illinois," and a generation-skipping transfer tax by reference to § 2604.48 It imposes no tax on the recipients of property. The figures on this page are the Illinois tax that applies when property passes at death.
The federal rate alongside
In the simplified case on this page, for one person with no earlier use of the exclusion, the federal estate tax estimate is 0.40 × (E − Illinois tax − federal exclusion) when that amount is positive.910 With the 2026 exclusion of $15,000,000, the federal tax is zero until E reaches $16,866,800, because the Illinois tax is subtracted first.7 Above that point, an added dollar of estate adds 13.79 cents of Illinois tax. It adds 0.40 × (1 − 0.1379), or 34.48 cents, of federal tax. Together that is 48.28 cents.
At E = $20,000,000 the federal tax is $1,080,414 and the two taxes together are $3,379,379, which is 16.9% of the estate. At E = $30,000,000 the federal tax is $4,528,690 and the two together are $8,206,966, which is 27.4%.
Rounding
The Attorney General's calculator stops when successive values differ by less than a dollar and reports whole dollars. Published figures can differ from the closed forms by up to about a dollar: $28 against $28.57 in the gift example, and $0 at E = $4,000,001 against $0.29.3
Not covered here
The derivation of both formulas, Form 700 line references, and the federal interaction in full, which are in the full calculation. Valuation, and the deductions that produce E. The tax situs of each asset. Senate Bill 3847, which would change the exclusion amount.6
