Cook County’s property tax system estimates what your home is worth for taxation, hears you out if you disagree, and turns the results into the tax bills it mails each cycle. The analyses below measure that machine’s steps — valuations, appeals, relief, exemptions, the bills and their delays — each from the records that analysis names. This page is the front door to them.
Nine analyses, built on the files and named statements each one cites · updated September 18, 2026Is the county’s valuation of your house right?
We matched 14,748 sales of houses and two-to-six-flats in 2025 to their tax-year-2025 valuations. The median valuation was 81 percent of what the buyer paid, and 60 percent for homes resold within two years of an earlier sale. The Assessor’s next citywide reassessment is scheduled for tax year 2027 on the office’s published cycle. Assessments against sale prices, by community area.
Should you appeal — and do you need a lawyer?
In 2025, Chicago homeowners who appealed at the Board of Review without a lawyer won a reduction 59.5 percent of the time; appeals filed by lawyers won 38.9 percent. Filing is free at both county offices. The lawyer-versus-alone numbers.
What happens after a first no?
The Assessor’s office turned down five appeals in six at stage one — and 93 percent of those parcels also appeared at the Board of Review, where 42.5 percent received the reduction stage one had refused. The two-stage appeal, followed parcel by parcel.
Who actually files?
Citywide, 17.5 of every 100 houses appealed for tax year 2025 — but nearly half of Lincoln Park’s houses did, against about one in 24 on the Southeast Side, and the low-filing areas won more often when they did file. The appeal map.
Where does the appeal relief go?
Appeals removed $3.85 billion of assessed value from Chicago’s 2025 roll. Measured against its own value, commercial property was cut 17.0 percent and residential 1.3 percent — thirteen to one. Within a shared taxing district, value removed from one class shifts relative burden toward the rest, though individual bills also turn on levies, exemptions and equalization. Where the reductions went.
Which parcels are exempt from property tax?
The assessor’s exempt list for tax year 2025 holds 93,641 parcels across Cook County — property that religious, charitable and educational organizations and governments can have exempted — and the City of Chicago holds 16,943 of them, 819 fewer than in 2022. By our reading of the owner names, nine of the ten largest holders are public bodies; the other is the Catholic Bishop of Chicago. Who holds the exempt list.
Why are the bills late?
Cook County was late on three of its last four second-installment deadlines — due dates of December 30, 2022, December 1, 2023, and December 15, 2025, with only 2024’s bill on schedule — and the tax year 2025 second installment, the bill due in 2026, is now set to run 61 days behind: the Treasurer’s table, as of August 17, 2026, lists October 1, 2026 as its due date. The county names its system modernization as the cause; CPS has said it is short $250 million while it waits, and the Treasurer’s office says at most $80 million. The full ledger of due dates · the late-collections dispute.
The other carrying cost
Property taxes are not the only carrying cost that moves on you. Illinois home insurance premiums rose 32 percent in four years, and the state’s new rate-review law, HB 4273, does not take effect until July 2027 — the analysis linked here reads the law’s own provisions and dates. The insurance arc.
How this hub works
Analyses join this page as they publish, and the figures above refresh whenever a piece is updated; tax-year-2026 numbers get a full revisit when the county certifies them. Every piece discloses its sources, its screens, and what it deliberately does not claim — including where we suppress thin data rather than guess. Nothing here is tax or legal advice; filing windows and forms live at the county’s own offices, linked from each analysis. If you spot an error anywhere in the cluster, corrections come first.