Cook County Property Tax Appeal: Results by Property Class
Some links pay us a referral fee; each one says so. Disclosure
Quick Answer
A Cook County owner can challenge an assessment at the Assessor, then at the Board of Review, then at the Illinois Property Tax Appeal Board or in court, and the county's own open data shows that the odds depend as much on whether your township was reassessed that year as on what you own. As of October 13, 2026 the latest full year in the Board of Review dataset is tax year 2025: 522,614 parcel appeals, 39.8% reduced, median cut 5.8% of assessed value (our aggregation). By class: multifamily of 7 or more units 10,923 appeals, 20.5% reduced, median reduction 14.7%; commercial and industrial 54,261, 27.6%, 16.1%; houses and row houses 51.1% and 6.5%; condominiums 31.6% and 2.8%. Pooled over 2021 to 2025, 60.7% of multifamily and 61.0% of commercial appeals won a reduction in a township reassessed that year, against 13.9% and 16.3% in the other two years of the three-year cycle. The clocks: a complaint at the Board of Review is due on or before 30 calendar days after the assessment list is published (35 ILCS 200/16-55(d)); an appeal to the Property Tax Appeal Board is due 30 days after the Board's notice or after it transmits its final action on the township to the assessor, whichever is later (35 ILCS 200/16-160). In the Board's 2026 session, Lyons, Northfield, Stickney and West Chicago close on November 6, 2026.
Key Takeaways
- Three forums, three clocks. The Assessor sets a filing date per township on its own calendar; the Board of Review takes complaints up to 30 calendar days after the assessment list is published (35 ILCS 200/16-55(d)) and says every township stays open at least 30 days; the Property Tax Appeal Board takes appeals within 30 days of the Board's notice or of its transmittal to the assessor, whichever is later (35 ILCS 200/16-160). The Board of Review says its jurisdiction is limited to the current year.
- Tax year 2025 at the Board of Review, by class (our aggregation of dataset 7pny-nedm): multifamily of 7 or more units 20.5% reduced with a median reduction of 14.7%; commercial and industrial 27.6% and 16.1%; houses and row houses 51.1% and 6.5%; apartments of 2 to 6 units 41.6% and 7.3%; condominiums 31.6% and 2.8%. The median is among appeals that won something.
- The reassessment year is the biggest lever in the data. Pooled 2021 to 2025, multifamily won in 60.7% of appeals when the township was reassessed that year and 13.9% otherwise; commercial and industrial 61.0% against 16.3%; houses 53.9% against 40.2%; condominiums 27.7% against 7.3%. Cook County reassesses one of three areas a year.
- Large reductions are concentrated in commercial and multifamily property: the middle half of commercial reductions in 2025 ran from 6.8% to 28.8% of assessed value, and across 2021 to 2025 the Board removed 17.64% of the assessed value that commercial appeals started with (our arithmetic from the dataset), against 4.01% for houses and 0.85% for condominiums.
- Appeals can go up: 4,375 of 2,487,301 Board of Review rows for 2021 to 2025 ended in an increase, 0.18% (our arithmetic). The statute allows the Board to raise an assessment after notice and a chance to be heard (35 ILCS 200/16-55(e) and (f)).
- A percentage cut in assessed value is the same percentage of market value inside one class, because the level of assessment is fixed by ordinance: 10% for classes 1, 2 and 3, 20% for class 4, 25% for classes 5a and 5b (Cook County Code section 74-64). An LLC or other corporate owner must be represented by counsel at the Board of Review (Board rule 1, as the Board's FAQ describes it).
- This page is analysis of public data, not advice. An Illinois property-tax attorney is the professional for an appeal; the numbers say what happened to others, not what will happen to one parcel.
CSV · 250 rows
Cook County property tax appeals 2021-2025: Board of Review and Assessor outcomes by property class and reassessment year, statutory deadlines, levels of assessment and the 2026 Board of Review calendar
250 rows: our aggregation of the Board of Review Appeal Decision History and the Assessor - Appeals dataset by class, year, reassessment status, triad and representation; the deadlines in 35 ILCS 200/16-55, 16-160, 16-180 and 16-185; the levels of assessment in Cook County Code section 74-64; the Board of Review 2026 township calendar.
Three places to appeal in Cook County, and the clock on each
Illinois lets a Cook County owner argue that an assessment is too high in sequence (35 ILCS 200/16-55 and 16-160). The Assessor reassesses a third of the county each year and hears appeals first; the Board of Review, which describes itself as “a separate, quasi-judicial agency independent of the Assessor”, hears the complaint next and sets the final county valuation for the tax year; the Property Tax Appeal Board (PTAB) or the circuit court comes last. The table is built from the statutes and the offices' own pages, all read and saved on October 13, 2026.
| Forum | Deadline | What the source says | Source |
|---|---|---|---|
| Assessor (appeal after the reassessment notice) | Set per township on the Assessor's calendar; no fixed statutory date found | The calendar says “Property owners are allowed to file an appeal with the Assessor's Office and at the Board of Review”; each township's last file date is listed separately | Assessor Assessment & Appeal Calendar (archived copy of December 10, 2025) |
| Board of Review | On or before 30 calendar days after publication of the assessment list | 35 ILCS 200/16-55(d) also gives a complainant not less than 10 business days to cure a complaint that does not follow the Board's rules, and the Board's FAQ says “All townships are opened a minimum of 30 days.” | 35 ILCS 200/16-55; Board of Review FAQ |
| Property Tax Appeal Board (PTAB) | 30 days after the Board of Review notice, or 30 days after the Board transmits its final action on the township to the assessor, whichever is later | No filing fee (“There is no charge for filing an appeal with the PTAB.”); appeals are de novo and not limited to the evidence given to the Board of Review | 35 ILCS 200/16-160 and 16-180; PTAB FAQ |
| Circuit court | Not stated in the sections we read | 35 ILCS 200/16-160 says a taxpayer “need not appeal the decision to the Property Tax Appeal Board before seeking relief in the courts”; filing at the PTAB bars valuation objections under sections 21-175 and 23-5 | 35 ILCS 200/16-160 |
Sources: Property Tax Code, 35 ILCS 200/16-55, 16-160 and 16-180 (ilga.gov, read through the Internet Archive because ilga.gov did not answer from our servers); Cook County Board of Review FAQ; PTAB FAQ and filing instructions; Assessor calendar page.
Three details in those sources are easy to miss. First, the Board's FAQ says it cannot hear an earlier year: “The Board’s jurisdiction is limited by law to the current year.” Second, the Board says an Assessor result does not tie its hands: “You are at no disadvantage if the Assessor has granted or denied a request to reduce the assessment.” Third, the PTAB's filing page tells Cook County filers who rely on the transmittal date to attach it: “you must also supply a copy of the date of transmittal.” The PTAB gives a plain warning about the clock: “the appeal must be filed within 30 days to be considered.”
What the Board of Review data says: appeals by property class, 2021 to 2025
The Board of Review publishes every appeal it decides as the open dataset “Board of Review Appeal Decision History” (7pny-nedm on the county's data portal; 6,933,428 rows from 2010 on). Each row is one parcel in one complaint, with the Assessor's certified assessed value, the Board's value and the result. We downloaded tax years 2021 to 2025 without parcel numbers, owner names or addresses, grouped the property classes by code, and counted three things for each group: appeals decided, the share with a reduction, and the median reduction among those reduced, measured as a percentage of the Assessor's certified total assessed value. The script and its printed output are saved with this page. The dataset's own warning applies throughout: “The values in this data are assessed values, NOT market values.”
The class groups follow the Cook County Code. Class 2 is real estate “used for residential purposes when improved with a house, an apartment building of not more than six living units, or residential condominium”, plus buildings of six or fewer units mixing commercial and residential use under 20,000 square feet of above-grade space. Class 3 is “All improved real estate used for residential purposes which is not included in any other class”, which for rentals means seven or more units. Class 5a is all real estate not in another class, which covers most commercial property, and class 5b is industrial.
Tax year 2025, the latest full year (appeals decided at the Board of Review):
| Property class | Parcel appeals decided | Distinct complaints | Share with a reduction | Median reduction among those reduced | Middle half of reductions |
|---|---|---|---|---|---|
| Multifamily, 7 or more units (class 3) | 10,923 | 7,002 | 20.5% | 14.7% | 7.7% to 26.5% |
| Commercial and industrial (class 5) | 54,261 | 24,737 | 27.6% | 16.1% | 6.8% to 28.8% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 40,867 | 39,257 | 41.6% | 7.3% | 5.0% to 10.7% |
| Houses and row houses (class 2) | 224,457 | 207,686 | 51.1% | 6.5% | 4.8% to 9.0% |
| Residential condominiums (2-99) | 182,456 | 8,269 | 31.6% | 2.8% | 1.7% to 4.8% |
| All classes in the dataset | 522,614 | n/a | 39.8% | 5.8% | 3.5% to 8.8% |
Source: Cook County Board of Review Appeal Decision History (dataset 7pny-nedm), our aggregation with analyze.py, run October 13, 2026. A “parcel appeal” is one row; a condominium building with 40 units filed by one attorney is 40 rows and one complaint, which is why condominiums show 182,456 parcel rows but 8,269 complaints. Reduction = (Assessor certified total assessed value minus Board total assessed value) divided by the Assessor value.
The pattern holds across the five years, with one swing that needs explaining. Share of appeals with a reduction, by tax year:
| Property class | Tax year 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|
| Multifamily, 7 or more units (class 3) | 45.7% | 28.1% | 27.8% | 47.8% | 20.5% |
| Commercial and industrial (class 5) | 43.8% | 29.0% | 30.8% | 37.8% | 27.6% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 44.0% | 37.9% | 36.1% | 50.4% | 41.6% |
| Houses and row houses (class 2) | 38.9% | 45.0% | 48.0% | 46.4% | 51.1% |
| Residential condominiums (2-99) | 12.5% | 10.1% | 10.4% | 33.0% | 31.6% |
| All classes | 28.3% | 28.4% | 33.3% | 39.5% | 39.8% |
And the median reduction among those reduced:
| Property class | Tax year 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|
| Multifamily, 7 or more units (class 3) | 19.8% | 20.3% | 20.0% | 16.2% | 14.7% |
| Commercial and industrial (class 5) | 20.9% | 19.4% | 19.2% | 17.7% | 16.1% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 9.2% | 8.3% | 7.8% | 7.8% | 7.3% |
| Houses and row houses (class 2) | 7.4% | 7.0% | 7.0% | 6.7% | 6.5% |
| Residential condominiums (2-99) | 4.6% | 2.9% | 3.1% | 2.6% | 2.8% |
| All classes | 7.9% | 7.1% | 7.2% | 5.5% | 5.8% |
Source: same dataset and script; each cell is one line of the saved output.
Two readings (our reading). The medians are stable: houses between 6.5% and 7.4%, condominiums between 2.6% and 4.6%, while commercial property moves between 16.1% and 20.9% and multifamily of 7 or more units between 14.7% and 20.3%. The shares are not stable, and the next section shows why.
Reassessment year against the other two years of the cycle
The Assessor's calendar says: “Cook County follows a triennial reassessment cycle, meaning that a property is reassessed once every three years.” The Assessor's Neighborhood Boundaries dataset assigns every township to one of three areas, which it calls triads: 8 townships in the City of Chicago, 13 in the north suburbs and 17 in the south and west suburbs. The Assessor's calendar says “In 2025, the north suburbs of Cook County will undergo reassessment”; its news page on the 2022 round says “Norwood Park Township is the first of thirteen townships located in the North Suburbs of Cook County which will be reassessed this year for Tax Year 2022.”; and its September 16, 2025 news page says it “published its report on the 2024 reassessment of property in Chicago.” By the three-year rhythm that puts the City in 2021 and 2024, the north suburbs in 2022 and 2025, and the south and west suburbs in 2023 and 2026 (our arithmetic). The Assessor's current calendar did not open from our servers, so we checked the mapping against the data itself: in every year, for multifamily and commercial property, the township group we call “reassessed” shows a far higher share of reductions, as the tables below show.
Pooled over 2021 to 2025, the same class of property fared very differently depending on whether its own township had just been reassessed:
| Property class | Township reassessed that year: appeals / share reduced / median reduction | Other two years of the cycle: appeals / share reduced / median reduction |
|---|---|---|
| Multifamily, 7 or more units (class 3) | 26,628 / 60.7% / 17.9% | 31,559 / 13.9% / 19.2% |
| Commercial and industrial (class 5) | 113,636 / 61.0% / 17.3% | 172,747 / 16.3% / 22.9% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 89,589 / 49.3% / 8.1% | 107,950 / 37.1% / 7.9% |
| Houses and row houses (class 2) | 418,165 / 53.9% / 6.8% | 529,113 / 40.2% / 7.0% |
| Residential condominiums (2-99) | 636,037 / 27.7% / 2.9% | 313,643 / 7.3% / 2.4% |
Source: dataset 7pny-nedm, our aggregation. “Reassessed that year” means the township's triad was reassessed in that tax year (City 2021 and 2024, north 2022 and 2025, south and west 2023); the south and west suburbs' 2026 round is not in the data yet.
For multifamily and commercial property the gap is wide, and it appears every year (share of parcel appeals reduced):
| Tax year | Multifamily 7+ units: reassessed township | Multifamily: other townships | Commercial and industrial: reassessed township | Commercial and industrial: other townships |
|---|---|---|---|---|
| 2021 | 58.3% | 14.0% | 61.3% | 21.0% |
| 2022 | 74.7% | 18.9% | 65.2% | 16.7% |
| 2023 | 68.4% | 12.0% | 62.4% | 16.6% |
| 2024 | 56.7% | 13.9% | 57.2% | 11.9% |
| 2025 | 73.1% | 10.6% | 63.1% | 15.4% |
Source: dataset 7pny-nedm, our aggregation.
In a reassessed township, between 56.7% and 74.7% of multifamily appeals and between 57.2% and 65.2% of commercial appeals ended in a reduction; in the other townships 10.6% to 21.0% did. Owners who won in the off years won bigger, with a pooled median reduction of 22.9% for commercial against 17.3% in reassessed townships (our reading: in an off year a parcel that wins usually has a specific problem, while in a reassessment year the Assessor's new value is itself what is being contested). The year-by-year shares in the first table swing for the same reason: 2025 was a north-suburbs reassessment year, so its county-wide multifamily share (20.5%) is low because most multifamily appeals that year came from townships in an off year.
Where the property is also matters. Pooled 2021 to 2025, by triad (share reduced / median reduction):
| Property class | City of Chicago (8 townships): share reduced / median | North suburbs (13 townships) | South and west suburbs (17 townships) |
|---|---|---|---|
| Multifamily, 7 or more units (class 3) | 36.1% / 18.2% | 41.1% / 17.6% | 28.3% / 18.4% |
| Commercial and industrial (class 5) | 36.8% / 20.6% | 37.5% / 15.9% | 25.4% / 18.7% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 44.4% / 8.1% | 38.0% / 6.6% | 35.6% / 8.8% |
| Houses and row houses (class 2) | 46.6% / 7.0% | 47.7% / 6.4% | 43.9% / 7.5% |
| Residential condominiums (2-99) | 19.7% / 2.7% | 25.0% / 3.1% | 17.2% / 2.9% |
Source: dataset 7pny-nedm, our aggregation; triads from the Assessor's Neighborhood Boundaries dataset (pcdw-pxtg).
As of October 13, 2026 the south and west suburbs are in their 2026 round by the same arithmetic: the Board of Review's 2026 file lists Oak Park, River Forest, Riverside, Berwyn, Cicero, Palos, Lyons and Stickney among its first groups, and 74,819 of the 137,551 rows the Assessor's appeals dataset already holds for tax year 2026 (54.4%, our arithmetic) are in south and west townships. Those appeals are not yet in the Board's dataset, so their outcome is unknown.
The Assessor stage: appeals before the Board of Review
The Assessor's own dataset, “Assessor - Appeals”, carries the mailed and certified values for each appealed parcel. Its description says “Appeals for many years are currently missing from this dataset”, and that “appeals from 2021 and after should continue to remain available”, so we used 2021 to 2025 and closed cases only. The reduction here is the mailed total assessed value minus the certified value after the Assessor's review.
| Property class | Assessor, tax year 2025: appeals / share reduced / median reduction | Pooled 2021-2025, reassessed year: share reduced / median | Pooled 2021-2025, other years: share reduced / median |
|---|---|---|---|
| Multifamily, 7 or more units (class 3) | 3,835 / 39.8% / 10.7% | 54.1% / 12.2% | 31.5% / 15.2% |
| Commercial and industrial (class 5) | 19,698 / 36.2% / 9.3% | 46.0% / 10.3% | 33.0% / 14.0% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 22,300 / 18.0% / 6.4% | 27.2% / 9.5% | 19.9% / 8.8% |
| Houses and row houses (class 2) | 169,409 / 17.5% / 5.7% | 23.8% / 7.3% | 15.2% / 7.3% |
| Residential condominiums (2-99) | 144,212 / 11.0% / 8.0% | 25.3% / 8.8% | 10.7% / 8.9% |
Source: Cook County Assessor - Appeals (dataset y282-6ig3), our aggregation with analyze.py. Closed appeals only; 2021 to 2025.
The Board of Review's “Assessor certified” column is the value after this stage, so the Board's reductions in the earlier tables come on top of whatever the Assessor gave. Measured as a share of all the assessed value that appeals started with, pooled 2021 to 2025:
| Property class | Assessor stage: assessed value removed as a share of appealed value | Board of Review stage: same measure |
|---|---|---|
| Multifamily, 7 or more units (class 3) | 11.87% | 12.85% |
| Commercial and industrial (class 5) | 12.44% | 17.64% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 3.91% | 4.10% |
| Houses and row houses (class 2) | 2.79% | 4.01% |
| Residential condominiums (2-99) | 4.01% | 0.85% |
Source: both datasets, our aggregation (sum of reductions divided by sum of starting assessed value, parcels appealed only).
Commercial property is the class where the Board removes more than the Assessor does (17.64% against 12.44%); for condominiums the Assessor stage does most of the work (4.01% against 0.85% at the Board). That is a pattern in the data, not a rule of the process (our reading).
Attorney or on your own: what the Board of Review data can and cannot say
The Board's dataset records whether a complaint was filed by an attorney or by an individual. Pooled 2021 to 2025:
| Property class | Filed by an attorney: appeals / share reduced / median | Filed by an individual (pro se): appeals / share reduced / median |
|---|---|---|
| Houses and row houses (class 2) | 665,670 / 42.2% / 6.6% | 281,603 / 55.8% / 7.3% |
| Apartments of 2 to 6 units and small mixed-use (2-11, 2-12) | 162,062 / 39.8% / 7.8% | 35,477 / 55.4% / 8.8% |
| Multifamily, 7 or more units (class 3) | 57,721 / 35.4% / 18.1% | under 1,000 appeals, not shown |
| Commercial and industrial (class 5) | 284,991 / 34.1% / 18.7% | under 1,000 appeals, not shown |
| Residential condominiums (2-99) | 937,298 / 21.0% / 2.8% | 12,382 / 13.5% / 4.6% |
Source: dataset 7pny-nedm, our aggregation, attorney code. Groups under 1,000 appeals are not shown.
Individuals won more often for houses (55.8% against 42.2%) and for small apartment buildings (55.4% against 39.8%). That does not mean an individual is better off without a lawyer (our reading): attorneys file large portfolios, including appeals on parcels a firm has little reason to expect to win, and individuals tend to file once, on a parcel they have looked at closely. The data cannot separate those effects. What it can show is the rule the Board states: individuals may represent themselves for “your own condominium, small apartment, mixed-use building or family business property (if it is held in your name)”, but “Properties held by corporations (LLC, LLP and any other corporate entities) must be represented by counsel”. For a rental house held in an LLC that rule decides the question; our LLC for rental property guide covers why landlords hold property that way. The same split shows in the table: nearly all commercial and multifamily appeals are attorney filings.
What a percentage is worth: the levels of assessment
The Cook County Code, section 74-64, sets the percentage of market value at which the Assessor assesses and the Board of Review reviews: “Class 1: Ten percent.”, “Class 2: Ten percent.”, “Class 3: Sixteen percent in tax year 2009, 13 percent in tax year 2010, ten percent in tax year 2011, and subsequent years.”, “Class 4: Twenty percent.”, “Class 5a: Twenty-five percent.” and “Class 5b: Twenty-five percent.” The Property Tax Code's general rule of 33 1/3% of fair cash value does not govern here: section 9-145 opens “Except in counties with more than 200,000 inhabitants which classify property for purposes of taxation”, and section 9-155 allows assessment “in accordance with a county ordinance adopted under Section 4 of Article IX of the Constitution of Illinois”. The incentive classes 6 to 9 and others have their own schedules in the same ordinance section.
| Class | Level of assessment | Assessed value that implies $2,000,000 of market value (our arithmetic) | A 16.1% cut in assessed value (the 2025 commercial median), our arithmetic |
|---|---|---|---|
| Class 2 (houses, up to 6 units, condominiums) | 10% | $200,000 | $32,200 of assessed value, 16.1% of market value |
| Class 3 (7 or more rental units) | 10% | $200,000 | $32,200 of assessed value, 16.1% of market value |
| Class 5a and 5b (commercial and industrial) | 25% | $500,000 | $80,500 of assessed value, 16.1% of market value |
Sources: Cook County Code of Ordinances section 74-64 (Municode, version of August 27, 2026); arithmetic ours. The $2,000,000 is an illustration, not a case.
Because the level is fixed within a class, a 14.7% cut in the assessed value of a multifamily building is a 14.7% cut in the market value the county applies to it (our reading), so the percentages in this page's tables carry straight across to value. What they do not give is the tax. The Board's FAQ is direct: “many factors other than your level of assessment including exemptions, local tax levies & tax rates, determine the amount of your tax bill.” It adds that the second installment bill “will not be issued until after your decision from the Board of Review has been received”. For a refund, the PTAB says it “does not issue, process, or control the payment of property tax refunds” and that in Cook County the Treasurer's Office handles them.
The 2026 Board of Review calendar
The Board of Review publishes a township calendar for its 2026 session as a PDF. The version dated August 2026, saved October 13, 2026, lists three groups so far; later groups are added to the Board's dates and deadlines page as they are scheduled.
| Group | Townships | Filing opens | Filing closes | Evidence submission deadline |
|---|---|---|---|---|
| 1 | Evanston, New Trier, Norwood Park, Oak Park, River Forest, Riverside, Rogers Park | August 3, 2026 | September 1, 2026 | September 11, 2026 (hearings October 5 to 7, 2026) |
| 2 | Berwyn, Cicero, Elk Grove, Lakeview, Maine, Palos | August 31, 2026 | September 29, 2026 | October 9, 2026 |
| 3 | Lyons, Northfield, Stickney, West Chicago | October 8, 2026 | November 6, 2026 | November 16, 2026 |
Source: Cook County Board of Review, “Board of Review Dates and Deadlines 2026 Session” (PDF, August 2026). Townships not listed had no dates in that file; the Board's FAQ says townships have “particular filing dates which vary annually”.
As of October 13, 2026, groups 1 and 2 have closed for filing; group 3 is open until November 6, 2026. Two statutory points on the Board's side: when a change of $100,000 or more in assessed value is sought, the Board must serve the petition on the taxing districts at least 14 days before the hearing, and any taxing district may intervene (35 ILCS 200/16-55(i)); and the Board must issue and send a decision once the complaint is heard (35 ILCS 200/16-55(d)), which is the notice that starts the PTAB clock.
Where this census is weak
- Rows are parcels. Condominium buildings and portfolios multiply rows. The tables show distinct complaints for 2025 so the scale is visible; the shares are shares of parcel rows.
- Only owners who appealed are in it. The 39.8% is not the chance that a randomly chosen Cook County parcel gets a cut; it is the share of appeals that did.
- Assessed values, not market values. Moving between them uses the levels in the previous section.
- The dataset does not show why a reduction was granted, what an owner spent on the appeal, or what a later PTAB or court step changed. Reductions at the PTAB and in court are outside these numbers.
- The cycle mapping is partly ours. Townships come from the Assessor's Neighborhood Boundaries dataset and the north (2022, 2025) and City (2024) years from the Assessor's pages; the City 2021 and south and west 2023 and 2026 years are our arithmetic from the three-year rhythm, supported by the data.
- Tax year 2026 is not decided yet. The Board of Review dataset was last updated on June 9, 2026, and the 2026 session is still running.
What a Cook County owner can do with this
This is analysis of public documents, not investment, legal or tax advice, and the decision points below describe what the sources show rather than telling anyone what to file.
- Find the township and the triad. The township is on the tax bill or the reassessment notice; the tables above split outcomes by the Assessor's three areas. Whether the township was reassessed that year moved the odds more than the property type did.
- Read the township's own dates. The Assessor's filing date and the Board's filing window are different dates, and the Board's windows are not set in advance.
- Decide who files. An individual can file for a house, a small apartment building or a mixed-use building held in his or her name; an LLC or other entity must use counsel (Board rule 1 as the FAQ describes it). The PTAB's FAQ lists who can appeal there: the owner, a taxpayer with a financial interest, an Illinois licensed attorney and a taxing body.
- Know what the Board asks for. The Board's FAQ says a picture of the property is required (Rule 18) and that evidence can be submitted up to 5 days before the hearing through its portal or the clerk's office; the commercial evidence guide is on the Board's site.
- Keep the later steps in view. The PTAB's window runs from the Board's notice or its transmittal, whichever is later (35 ILCS 200/16-160), and the Board can also raise an assessment after notice (35 ILCS 200/16-55(e) and (f)).
The professional for an appeal is an Illinois property-tax attorney, who can look at the specific parcel, the comparable sales and income evidence and the cost of the filing. This page does not recommend a lawyer or a filing. A financial-adviser match is not the right door for this question, so there is none here.
Update alert · free
An email when the Cook County property tax appeal rules and results numbers change
When a rate, rule or filing behind this page changes: what changed, the one number that matters, and the source to check it yourself.
For other states, deadlines and forums differ county by county; our national property tax appeal guide covers them.
Questions people ask about Cook County property tax appeals
Sources, read and saved on October 13, 2026: Cook County open data (datacatalog.cookcountyil.gov): Board of Review Appeal Decision History (7pny-nedm), Assessor - Appeals (y282-6ig3) and Assessor - Neighborhood Boundaries (pcdw-pxtg); Cook County Board of Review website: FAQ, residential and commercial appeal pages, “Dates and Deadlines 2026 Session” (PDF, August 2026); Illinois Property Tax Code, 35 ILCS 200/9-145, 9-155, 16-55, 16-95, 16-160, 16-180 and 16-185 (ilga.gov, through the Internet Archive); Cook County Code of Ordinances Chapter 74, Article II, Division 2, sections 74-60 to 74-64 (Municode, version of August 27, 2026); Cook County Assessor: assessment classification sheet, Assessment & Appeal Calendar (archived copy of December 10, 2025), the 2022 north suburbs and 2024 Chicago reassessment news pages and the valuation reports page (archived copies); Illinois Property Tax Appeal Board: FAQ, filing instructions and Cook County refund notice. The Assessor's own site (cookcountyassessoril.gov) blocked our servers, so its pages were read from Internet Archive copies. This is analysis of public documents, not investment, legal or tax advice.
Keep reading.
- 0123 min read
506b vs 506c: 30% of Real Estate Form Ds Now Choose 506(c)
How filers actually choose between Rule 506(b) and 506(c), counted from the SEC's Form D data: 35,494 real estate notices from January 2019 to September 2026, with the 506(c) share rising from 16.7% to 30.2% in 2025 (10.3% across all industries). Plus what each choice does to offering size, minimum, unsold offerings and non-accredited buyers, the verbatim rule text and the staff's March 12, 2025 letter on verification.
- 0219 min read
Bank Statement Loans 2026: Requirements, Terms and the Law
What seven lenders' own websites say a bank statement loan requires (October 13, 2026): minimum scores of 620 to 640, up to 90% loan-to-value, expense factors from 10% to 70%, plus what Regulation Z says about prepayment penalties, escrow and ability to repay, and how much bank statement and DSCR lending Redwood Trust's Aspire unit reported for 2026.
- 0320 min read
Commercial Real Estate Loan Rates 2026: 987 SEC-Filed Loans
Commercial real estate loan rates as of October 13, 2026, read from the SEC filings of 29 CMBS trusts: 987 fixed-rate loans, median 6.54% on 5-year and 6.27% on 10-year loans, by property type, size and month, with the Treasury spread, bridge-lender coupons and SBA rates.