The last time Chicago was reassessed, in tax year 2024, the Cook County Board of Review ruled on 324,618 residential parcels in the city's eight townships. It lowered the assessment on 135,603 of them: 41.8 percent. Where it cut, the median reduction was 4.1 percent of assessed value.
The city is next on the county's three-year rotation, in 2027. When the notice comes, the window is short. In 2026, the eight city townships had 42 to 46 days from the Assessor's notice date to the last file date, and the Board's windows ran about a month. Most of the work does not have to wait for the notice.
Quick Answer
Cook County reassesses one region every three years. Chicago was last reassessed in 2024, and on that rotation the city's eight townships are next in 2027. In 2024, the Board of Review cut 41.8% of the residential assessments it ruled on in the city. Use the months before the notice to fix record errors, claim missing exemptions and gather evidence, so the short window goes to deciding rather than scrambling.
The rotation, and where Chicago sits
Cook County splits into three regions, each reassessed every third year:
- City of Chicago: 2018, 2021, 2024, and next in 2027
- North suburbs: 2025, then 2028
- South and west suburbs: 2026, then 2029
Chicago's eight townships are Hyde Park, Jefferson, Lake, Lake View, North, Rogers Park, South and West. The order in which they receive notices can change from cycle to cycle, so do not assume your township will mail when it did in 2024.
What the last three city reassessments produced
Residential decisions at the Board of Review, City of Chicago, in each reassessment year:
- 2018: 311,663 residential decisions; 151,992 reduced (48.8%). Owners filed 6.9% themselves, and 67.0% of those were reduced.
- 2021: 290,030 residential decisions; 69,488 reduced (24.0%). Owners filed 6.2% themselves, and 55.3% of those were reduced.
- 2024: 324,618 residential decisions; 135,603 reduced (41.8%). Owners filed 6.4% themselves, and 61.8% of those were reduced.
Three things to take from it.
The rate swings by cycle. From 48.8 percent to 24.0 percent and back to 41.8 percent. Nobody can tell you the 2027 number. Plan on making a case, not on a rate.
Few owners file their own appeals. Owners filed only 6 to 7 percent of city residential decisions in each cycle. Those owners were reduced more often than attorney filings (61.8 percent against 40.4 percent in 2024). That is not proof that filing yourself works better. A firm files a whole book of parcels; an owner who files alone has picked one home. It does show that an owner with evidence is not shut out.
The volume is real. Counting every property class, the Board issued 372,847 city decisions for 2024, more than double the 154,898 of 2023. The Assessor said residential assessments in the city rose 18 percent in total in the 2024 reassessment. That figure is total growth, not the change on a typical home.
Your township, 2024
Residential decisions and the share reduced at the Board:
- Hyde Park: 14,066 decisions, 44.4% reduced
- Jefferson: 47,552 decisions, 46.7% reduced
- Lake: 16,715 decisions, 54.8% reduced
- Lake View: 69,816 decisions, 49.6% reduced
- North: 64,303 decisions, 31.8% reduced
- Rogers Park: 11,528 decisions, 41.4% reduced
- South: 48,492 decisions, 30.3% reduced
- West: 52,146 decisions, 45.0% reduced
These are history for one cycle, not odds for your home.
What you cannot do yet
There are no 2027 values yet, so there is nothing to appeal for 2027. The Assessor builds them from market data, including recent sales, and publishes the schedule when it is ready.
2026 is a different decision. City windows that open in 2026 apply to 2026 values, in a year that is not a city reassessment year. The Assessor's 2026 calendar had three city townships open into late fall: Jefferson until November 12, North until November 24 and South until December 15. If you have a real issue with your 2026 value and your township is still open at the Assessor or the Board, file it there. Do not file only to "practice" for 2027.
Seven things you can do now
1. Read your property record card. Check square footage, bedrooms, bathrooms, basement finish, garage and property class. A wrong fact carried into a reassessment model can inflate the value. See how to find record card errors.
2. Check the exemption lines on your last bill. The second-installment bill lists the homeowner, senior and senior freeze exemptions applied. If one is missing and you were eligible, tax years 2021 through 2025 can currently be claimed through a Certificate of Error.
3. Start a condition folder. Dated photos of problems the county cannot see, such as foundation cracks, water damage or an original kitchen, plus repair estimates and inspection reports. This is the evidence that supports a market-value argument.
4. Keep your purchase papers handy. If you bought in the last few years in an arm's-length sale, your closing statement is strong evidence of value. See your closing price is evidence.
5. Watch nearby sales. Note sales of homes similar to yours, and in condo buildings, sales in your building. You want comparisons that are recent when the notice arrives.
6. Know how your notice will reach you. Make sure the Assessor has a current mailing address. The last file date is printed on the notice, and there are no extensions.
7. Decide how you would file. You can file yourself, use a flat-fee packet, or hire an attorney. Comparing those now keeps you from signing a percentage agreement in a rush. See the property-tax appeal fee math report.
If you won a reduction in 2024
For an owner-occupied home, a 2024 Board of Review reduction generally held for 2025 and 2026. The 2027 reassessment starts from a fresh value. When the notice comes, compare it with the value you won.
Condo owners
Condos have their own wrinkles. Each unit, parking space and storage space can carry its own PIN, and the association may file for the building. See condo PIN confusion and condo association appeals.
The numbers behind this article
Decision counts and rates are Censum's tabulation of the Cook County Board of Review Appeal Decision History dataset, accessed November 7, 2026. They count PIN-level decisions, one per parcel, not complaints, and cover the Board stage only, not Assessor appeals. "Residential" is the dataset's major class and includes condominium units. Township codes 70 to 77 were matched to names using the Assessor's parcel data.
FAQ
Will my 2027 assessment go up?
Nobody knows yet. The value depends on the Assessor's 2027 model and the market data behind it. Some homes go up more than the city average, some less, and some go down.
Can I appeal my 2027 value now?
No. You can appeal only once a value is issued and a window opens. You can prepare evidence now.
How often did the Board cut city home assessments last time?
In tax year 2024, it reduced 135,603 of 324,618 residential decisions in Chicago, 41.8%. In 2021 the rate was 24.0%, and in 2018 it was 48.8%. Past rates are history, not a forecast.
When will the notices mail?
The Assessor publishes the calendar township by township. Check the official assessment calendar in early 2027.
Does a reassessment raise my tax bill by the same percentage?
No. The notice changes your value. Your bill also depends on the state multiplier, exemptions and local tax rates, and rates adjust when values across the city rise.
Sources
- Cook County Assessor, Assessment Calendar and Deadlines
- Cook County Assessor, 2024 Chicago reassessment final data
- Cook County Assessor, "Assessor's Office Releases 2024 Chicago Reassessment Report," September 16, 2025
- Cook County Assessor, Certificates of Error
- Censum tabulation of the Cook County Board of Review Appeal Decision History dataset (Cook County open data), accessed November 7, 2026; PIN-level decisions.
Next step
Run the free check now to see how your Chicago home's current assessment compares, and run it again when the 2027 notice arrives. Check my Chicago property
Censum LLC is a data and analytics company, not a law firm and not a tax advisor. You file your own appeal. Censum is independent and is not affiliated with Cook County or any government agency.