Your home, savings, business and other assets can add up over time. Understanding how Illinois estate tax may affect what you leave behind can help you make thoughtful choices for the people you love.
Use this Illinois estate tax calculator to explore a 2026 planning estimate for a simple Illinois-resident estate. Start with your gross estate value and allowable deductions, then use the result to prepare for a conversation with an estate-planning attorney.
This calculator provides an educational estimate. It does not provide legal or tax advice, prepare a return, or determine filing requirements. Have an attorney review your estate and any deductions before relying on the result.
How to use the calculator
1. Enter your gross estate value
Enter the dollar value of assets included in your estate at death, before deductions. Depending on ownership and other facts, this may include real estate, bank and investment accounts, retirement accounts, business interests and certain life insurance proceeds.
An estate-tax inventory can include assets that pass directly to a beneficiary or through a trust. Start with a complete list and ask your attorney which amounts belong in the calculation. For planning today, approximate values can help you explore a scenario; a tax return may require formal valuations.
2. Enter allowable deductions
Enter qualifying debts, administration expenses, and any allowable marital or charitable deductions. Each has eligibility rules. Avoid counting a debt twice by subtracting it from an asset’s value and entering it again as a deduction.
Leave Illinois estate tax out of this field. The calculator accounts for that deduction as part of its calculation. Do not enter the $4 million exclusion as a deduction. If you are unsure what qualifies, ask your attorney before treating a figure as your expected tax bill.
3. Confirm that the assumptions fit
This version models a death in 2026 involving an Illinois resident, with all assets in Illinois, no adjusted taxable lifetime gifts, and no special elections or tax credits. It calculates one person’s estate. It does not combine a couple’s assets or calculate federal estate tax.
If those assumptions fit, select the confirmation box and calculate your estimate. You can change the amounts and calculate again to compare scenarios. If an assumption does not fit, or you are unsure, request an individual review.
Understanding the Illinois estate tax exclusion in 2026
Illinois currently uses a $4 million estate-tax exclusion. The state’s rules are separate from federal estate-tax rules, so an estate may face Illinois tax even when no federal estate tax is due. The exclusion is established in Illinois law.
Illinois uses an interrelated calculation that accounts for the estate tax itself as a deduction. A graduated tax schedule and a limiting calculation affect the result. Multiplying the amount above $4 million by a flat 16% will not produce a reliable estimate. The Illinois Attorney General’s calculator provides the state’s calculation tool.
For the simple scenario supported here, the estimate is zero when the estate value after other allowable deductions is $4 million or less. Filing requirements must still be checked separately.
An example with a 5 million dollar estate
Suppose an Illinois resident dies in 2026 with a $5 million gross estate, all assets in Illinois, no allowable deductions entered, no adjusted taxable gifts, and no special elections or credits.
The estimated Illinois estate tax is $285,714, rounded to the nearest dollar. The amount remaining after this estimated tax is $4,714,286, before any costs or obligations omitted from the example.
This example illustrates the calculation under those assumptions. Your result can change when ownership, deductions, lifetime gifts or other facts change.
Compare a few simple estate examples
These examples assume a death in 2026, an Illinois resident with all assets in Illinois, no other allowable deductions, no adjusted taxable lifetime gifts, and no special elections or tax credits. Estimates are rounded to the nearest dollar.
| Gross estate | Estimated Illinois tax |
|---|---|
| $4,000,000 | $0 |
| $4,100,000 | $28,571 |
| $5,000,000 | $285,714 |
| $6,000,000 | $456,071 |
| $10,000,000 | $926,923 |
The example just above $4 million shows why a flat percentage of the estate is not a reliable shortcut. Different deductions or circumstances can change the result. A zero estimate does not determine whether a return must be filed.
When an individual review is important
Please get a separate calculation if the estate includes property outside Illinois, the person was a nonresident, or there were adjusted taxable lifetime gifts. Special elections, including an Illinois QTIP election for qualifying property passing to a spouse, also need individual review. Property subject to a prior spouse’s Illinois QTIP election also needs individual review.
The calculator does not calculate other states’ taxes, gift tax, generation-skipping transfer tax, penalties, interest or deadlines. It cannot determine whether a particular trust or transfer achieves your planning goals.
Common questions
Does a zero estimate mean no Illinois return is required
No. The Illinois Attorney General explains that Form 700 is required when the gross estate plus adjusted taxable gifts exceeds $4 million, even when no federal return is required. Deductions may reduce the tax without removing a filing obligation. Review the state’s instructions with your attorney.
How is federal estate tax different
For a U.S. citizen or resident who dies in 2026, the federal basic exclusion amount is $15 million. Lifetime taxable gifts and other circumstances can affect the federal analysis. The IRS explains the rules in its Form 706 instructions. This calculator estimates Illinois estate tax only.
Do married couples automatically get an 8 million dollar Illinois exclusion
Illinois does not provide federal-style portability of a deceased spouse’s unused exclusion. Simply being married does not automatically give the surviving spouse an $8 million Illinois exclusion. Asset ownership, trust provisions and marital deductions need coordinated review. Federal portability has its own election and filing rules.
Can a trust help with estate tax planning
A trust’s tax effect depends on its terms, funding and the rights you retain. A revocable trust generally does not remove its assets from your gross estate for estate-tax purposes. Some irrevocable trust strategies may help, but they can involve significant changes to ownership and control. Discuss the tradeoffs before transferring assets.
Are the numbers I enter saved
The calculator runs in an isolated browser frame. It does not send your entries or results to the website or its analytics. Site analytics may still record a page visit. Clear removes the amounts and results from the calculator.
Sources and review date
Technical checks completed October 14, 2026. Calculation spot checks, input validation, privacy isolation, and desktop and mobile-width layouts were tested. These technical checks are not an attorney’s approval of the calculator or of your individual tax position.
The calculation and explanations reference the Illinois Attorney General’s estate tax calculator, the Illinois estate tax instructions, and the IRS Form 706 instructions for federal context. This tool estimates Illinois tax only. Its stated coverage is 2026; the rules and year-specific content need review before it is used for a later year.
Related estate-planning reading
Learn about tax-free gifts and the differences between revocable and irrevocable trusts. Probate administration costs are separate from estate tax; use our Illinois probate cost calculator to explore those costs and build a budget from amounts you know.
Plan your next step with confidence
Whether your estimate is zero or shows a potential tax, it can help you identify questions worth asking. Bring an asset list, approximate values, debts, beneficiary designations, existing estate documents and records of lifetime gifts to your planning conversation.
At Plan Forward Legal, we help individuals and families build Illinois estate plans around their circumstances and the people they want to protect. We can review how estate-tax planning fits into your broader plan.