Illinois estate tax, inheritance tax & probate costs

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 permanent federal $15M exemption, 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.