Overview of Illinois Estate Tax Laws

Understanding How Illinois Estate Taxes Affect an Estate

If you live in Illinois, then you live in one of a handful of states that still collect a state death tax. The estates of Illinois residents, as well as the estates of nonresidents who own real estate and/or tangible personal property located in Illinois, are subject to a state death tax under the following guidelines.

NOTE: State laws change frequently, and the following information may not reflect recent changes. For current tax or legal advice, please consult with an accountant or an attorney since the information contained in this article is not tax or legal advice and is not a substitute for tax or legal advice.

How have the Illinois estate tax rules changed in the past few years?

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The Illinois estate tax rules have changed significantly in the past few years. In 2009 the Illinois estate tax exemption was $2,000,000. In 2010 the Illinois estate tax was repealed due to changes in the federal estate tax laws. The Illinois legislature acted quickly in 2011 to reinstate the ​state estate tax with a $2,000,000 exemption. Then, in December 2011, the Illinois legislature acted to raise the estate tax exemption to $3,500,000 for 2012 and $4,000,000 for 2013. The information presented below applies to deaths that occur in 2012 only.


When is an estate subject to the Illinois estate tax?

For Illinois residents, a 2012 estate may be subject to the Illinois estate tax if the total gross estate exceeds $3,500,000.

For nonresidents of Illinois, a 2012 estate may be subject to the Illinois estate tax if it includes real estate and/or tangible personal property having a situs within the state of Illinois and the gross estate exceeds $3,500,000.

What Illinois estate tax forms must be filed?

The estate representative of a 2012 estate that is subject to the Illinois estate tax must file an Illinois Estate & Generation-Skipping Transfer Tax Return, Form 700, as well as a federal estate tax return, IRS Form 706, and United States Estate (and Generation-Skipping Transfer) Tax Return (or any other form containing the same information), even if the estate is not required to file IRS Form 706. IRS Form 706 must include all schedules, appraisals, wills, trusts, attachments, and so on, as the Federal Form 706 would have for a 2011 decedent with a tentative taxable estate plus adjusted taxable gifts over $2,000,000. The Illinois estate tax will then be determined using the interrelated calculation for 2012 decedents as discussed below.

Note that when the 2012 tentative taxable estate plus adjusted taxable gifts exceed $5,120,000, Illinois Form 700 is to be prepared in the same manner for 2012 as for 2011, and must, therefore, include a copy of IRS Form 706 with all attachments.

Are transfers to a surviving spouse taxable?

Outright transfers to a surviving spouse are not taxable.

For married couples who have used AB Trust planning to reduce their federal estate tax bill, an Illinois death tax may be due on the B Trust after the first spouse's death due to the gap of $1,620,000 between the Illinois exemption of $3,500,000 and the federal exemption of $5,120,000. Nonetheless, a married decedent's estate can make an election to treat a trust of which the surviving spouse is the sole beneficiary as "qualified terminable interest property" (QTIP) for purposes of calculating the Illinois estate tax. Thus, married Illinois residents can defer payment of both Illinois and federal death taxes until after the death of the surviving spouse using ABC Trust planning.

When are the Illinois estate tax return and tax payment due?

The Illinois estate tax return must be filed, and any estate tax due must be paid, within nine months after the decedent's date of death.

An extension of time to file the Illinois estate tax return and related forms and pay any tax due may be requested; however, this will not extend the time to pay the tax, and interest will accrue during the extension period.

Where should I file the Illinois estate tax return and make the tax payment?

For Cook, DuPage, Lake, and McHenry Counties file the original of the return with:

Office of the Attorney General

Revenue Litigation Bureau
100 West Randolph Street
13th Floor
Chicago, IL 60601

For all other counties, file the original of the return with:

Office of the Attorney General
Revenue Litigation Bureau
500 South Second Street
Springfield, IL 62706

Effective July 1, 2012, an additional copy of the return, without attachments, must also be filed with the state treasurer as indicated below.

Effective July 1, 2012, all estate tax payments should be directed to one of the state treasurer’s offices, which is encouraging people to mail the applicable returns, attachments, and payments to the Springfield office; however, taxes may be paid in person at either office indicated below:

By mail or in person:

Illinois State Treasurer
Estate Tax Division
400 West Monroe, Suite 401
Springfield, IL 62704

In person:

Illinois State Treasurer
100 West Randolph Street
Suite 15-600
Chicago, IL 60601

How is the Illinois estate tax calculated?

The Illinois estate tax is determined using the interrelated calculation. For both resident and nonresident decedents, the tax base will be calculated assuming all assets are located within Illinois. (Line 6, Schedule A or B, Form 700). The percentage of Illinois assets to total assets is then computed with the percentage applied to the tax base for apportionment purposes to determine the amount of Illinois estate tax due.

For deaths that occurred on or after January 1, 2012, use the following calculator provided by the Illinois Attorney General's office to calculate the tax due: 2012 Decedent Estate Tax Calculator.

Where can I find additional information about Illinois estate taxes?

For more information about Illinois estate taxes, including information for the estates of decedents who died in 2011 and prior years, refer to the Illinois Attorney General's Estate Tax web page. For more information about estate tax payments, refer to the Illinois Treasurer's Inheritance Tax and Estate Tax web page.