Illinois Estate & Inheritance Tax

What the Illinois Estate Data Reveals

Illinois layers a state estate tax on top of the federal regime — exemption of $4,000,000 with rates from 0.8% to 16%, and spousal portability is not recognized. For estates above this state threshold but below the federal $13,990,000 exemption (2025), state law is the binding constraint, which is exactly the bracket most affluent households fall into. There is no separate inheritance tax, so beneficiaries receive their share without a second state-level deduction at distribution.

IRS Statistics of Income data show 302 federal estate tax returns filed by Illinois residents in the most recent available year (filing year 2023), reporting $8.56 billion in combined gross estate value. Net federal estate tax paid totaled $0.49 billion that year. Across the multi-year IRS SOI series above, Illinois averages roughly 259 taxable filings per year, with an effective federal rate on reported gross estates of about 7.8%.

Probate itself typically runs 9–18 months in Illinois (roughly 14 months on average), with court filing fees of $238–$500. Attorney fees are negotiated rather than statutory, so engagement letters and hourly-vs-flat structures matter more to the total bill. Illinois does offer a simplified small-estate track for estates under $100,000, which most families use to bypass full formal probate. Because Illinois has not adopted the UPC, probate practice can vary materially by county and judicial district. As a common-law (separate property) state, Illinois treats each spouse's holdings individually unless jointly titled, so titling choices drive what actually enters the probate estate.