What is the Illinois estate tax?

Illinois imposes a state-level estate tax on estates valued above $4 million. Unlike the federal estate tax, which has a 2026 exemption of $15 million per individual, Illinois’ exemption has not been adjusted for inflation since 2012. The tax is calculated on a graduated schedule with rates up to approximately 16%.

Does Illinois have an inheritance tax?

No. Illinois does not have an inheritance tax, which means your beneficiaries do not owe tax when they receive assets from your estate. The estate itself, however, may owe Illinois estate tax before assets are distributed.

What is the “cliff” effect in Illinois estate tax?

Illinois uses a cliff structure, meaning that as soon as an estate exceeds $4 million, the entire estate — not just the amount above the threshold — becomes subject to tax. This is different from the federal system, which taxes only the amount above the exemption.

Should I create a credit shelter trust to reduce Illinois estate tax?

A credit shelter trust (also called a bypass trust) is often recommended for married Illinois couples because the state doesn’t offer portability between spouses. Without this structure, a surviving spouse may lose the first spouse’s $4 million exemption. A qualified estate planning attorney can determine whether a credit shelter trust is appropriate for your situation.

Should I use an LLC to hold Illinois real estate if I’m not an Illinois resident?

Holding Illinois real estate through an LLC may help nonresidents convert otherwise taxable real property into intangible property that falls outside Illinois estate tax for nonresidents. This strategy involves legal and tax considerations and should be reviewed by a qualified advisor before implementation.

Should I make lifetime gifts to reduce my Illinois estate?

Lifetime gifting can be an effective way to reduce your taxable estate because Illinois has no state gift tax. Annual exclusion gifts — currently $19,000 per recipient in 2026 — and larger gifts may reduce your estate’s value and remove future appreciation from your estate. Consult with a tax professional to understand how gifts may affect your overall estate plan.

Where can I find help with Illinois estate tax planning?

Mercer Advisors estate planning specialists can evaluate your Illinois estate tax exposure and work with your wealth advisor and tax team to identify strategies suited to your situation. You can learn more or schedule a conversation at merceradvisors.com.

Where do I file an Illinois estate tax return?

Illinois estate tax returns are filed with the Illinois Office of the State Treasurer. The return is due within nine months of the decedent’s death. An estate planning attorney or qualified tax advisor can assist with preparation and filing.

How does Illinois estate tax compare to the federal estate tax?

The two systems differ significantly. The 2026 federal exemption is $15 million per individual, indexed for inflation, and the federal system offers portability between spouses. Illinois’ exemption is $4 million, has not been adjusted for inflation since 2012, and offers no portability. The federal system taxes only the amounts above the exemption; Illinois uses a cliff structure that taxes the entire estate as soon as the threshold is crossed.

Is a will or a trust better for reducing Illinois estate tax?

A trust generally offers more planning flexibility than a will when it comes to Illinois estate tax. A revocable living trust alone doesn’t reduce estate tax, but irrevocable trusts — such as credit shelter trusts or irrevocable life insurance trusts — can help remove assets from the taxable estate or preserve both spouses’ exemptions. The right approach depends on your specific situation and goals.

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