Chicago, Illinois
Cook County commercial property tax appeals
Appeals start with the Cook County Assessor's Office and go to the Cook County Board of Review. Here is how commercial evidence is built, filed and heard in Cook County.
- Assessor
- Cook County Assessor's Office
- First-level board
- Cook County Board of Review
- Filing deadline
- Assessor: 30 calendar days beginning on the date Notices of Proposed Assessed Valuation are issued for the township (the last file date is printed on the notice). Board of Review: the township's filing window, set by the Board each year and open at least 30 days
- Commercial assessment level
- 25% of market value (Class 5a commercial and Class 5b industrial); 10% for Class 3 apartment buildings of seven or more units
- Value standard
- Fair cash value (35 ILCS 200/1-50)
- Valuation date
- January 1 of the assessment year (lien date)
- Assessment cycle
- Triennial reassessment rotating by triad: City of Chicago (2024), north and northwest suburbs (2025), south and southwest suburbs (2026)
- Notices mailed
- Township by township through the year; each township's reassessment notice date and last file date are posted on the Assessor's assessment and appeal calendar
How Cook County assesses commercial property
Cook County runs the most layered commercial appeal system in the country. The Assessor's Office reassesses one triad each year (the City of Chicago, the north and northwest suburbs, and the south and southwest suburbs in rotation), so every parcel gets a fresh market value once every three years, and that reassessment sets the base an owner lives with until the next cycle. Commercial and industrial property is assessed at 25% of fair cash value under the county classification ordinance, Class 3 apartment buildings at 10%, and the Illinois Department of Revenue's equalization factor is applied to the county total afterward.
Owners get two local chances. The first is the Assessor, where the township's filing period runs about 30 days from the date its reassessment notices are issued, and every appeal on income-producing property must arrive with RPIE income and expense data. The second is the Board of Review, a three-commissioner body that opens townships in groups and accepts complaints every year, including years with no reassessment. Corporations and LLCs must appear at the Board through an Illinois attorney, and the Board applies its written rules on Schedule E history, vacancy affidavits and USPAP appraisals strictly.
If the Board does not deliver, the next stop is the Illinois Property Tax Appeal Board within 30 days of the Board's decision, or a tax objection in circuit court after the bill is paid. For a consultant building packets here, the work is mostly income work: a normalized three-year operating history, a supportable market rent and vacancy, and a cap rate the Assessor's own published model has to answer.
Major commercial submarkets
- Chicago Loop and River North office
- Fulton Market and West Loop
- O'Hare and Elk Grove Village industrial
- Schaumburg and the northwest suburbs
- I-55 and Bedford Park industrial corridor
- South suburban industrial (Chicago Heights, Harvey)
Uniformity authority
Ill. Const. 1970, art. IX, §4(a) (uniform taxation by valuation) and §4(b) (Cook County classification ordinance)
Appeal statute
35 ILCS 200/16-95 (Board of Review, counties of 3,000,000 or more); 35 ILCS 200/16-160 (Property Tax Appeal Board)
After the board
Illinois Property Tax Appeal Board (PTAB) within 30 days of the Board of Review's written notice of decision, or of the Board's transmittal of the township to the Assessor, whichever is later; alternatively a tax objection complaint in the Circuit Court of Cook County after the taxes are paid
Official forms ATALI ELECTRIC fills for Cook County
| Form | Filed with | Purpose |
|---|---|---|
| Assessor commercial appeal (SmartFile) with RPIE statement | Cook County Assessor's Office | First-level appeal of the proposed assessment. The Real Property Income and Expense (RPIE) filing is required for income-producing property, or the appeal is deemed incomplete and is not evaluated. |
| Board of Review complaint | Cook County Board of Review | Second-level appeal filed during the township's open window, with supporting evidence uploaded by the Board's evidence deadline. |
| Board of Review Attorney Authorization Form | Cook County Board of Review | Authorizes the Illinois attorney filing for the owner. It must be submitted before the complaint is finalized; late authorizations are not accepted and the form may not be altered. |
| Vacancy-Occupancy Affidavit | Cook County Board of Review (the Assessor also asks for a notarized vacancy affidavit) | Supports vacancy relief together with dated interior photographs, an affidavit on the duration of and reason for the vacancy, and proof of leasing efforts. |
Filing system: Assessor: SmartFile online appeals with the RPIE Online Form; Board of Review: Digital Appeals Processing System (DAPS) portal
Hearings and evidence
Assessor appeals are decided on the written record by the office's commercial valuation staff. At the Board of Review, analysts review commercial complaints on the documents; attorneys may argue at hearing calls scheduled by the Board, limited to eight dockets per call, and failure to appear waives oral argument. A re-review request must be filed within 3 days of the Board's letter and cannot raise a new legal theory.
- 01Assessor: the appeal and all supporting evidence must be filed by the township's closing date, and RPIE data for income-producing property is due by the same date. Nothing is accepted after the township closes except in a system error.
- 02Board of Review Rule 20: leased or leasable property must include Schedule E of Form 1040 for the three years before the lien date, or an affidavit plus a property-level income and expense statement; for multi-tenant buildings the Board will consider lease summaries, audited financial statements and rent rolls with totals.
- 03Board of Review Rule 19: appraisals must follow USPAP, be prepared by an Illinois licensed or certified appraiser, value the property as of the January 1 lien date, include an income approach for income-producing property (or explain its omission), and disclose any appraisal made within three years before the lien date.
- 04Board of Review Rule 14(B): a complete Historical Summary Form is required for income-producing property other than Class 2 residential.
- 05Board of Review Rule 21: vacancy relief requires the Vacancy-Occupancy Affidavit, dated interior photographs of the vacant space, and documentation of leasing efforts.
Income evidence
Cook County is the most income-driven jurisdiction in this guide. The Assessor values most commercial and Class 3 apartment property with income models built on market rent, vacancy, expense and cap rate assumptions by property type and township, and it collects actual operating data through RPIE. On appeal, actual income alone rarely carries the case: the Board of Review and PTAB give weight to operating history when rent, vacancy and expenses are shown to reflect the market, and appraisal income approaches must use cap rates drawn from current market data. Convert the indicated market value to assessed value at the 25% class level before comparing it to the notice.
Practitioner notes
- The reassessment year sets the base for the triad's three-year cycle. A reduction won at the Assessor in the reassessment year generally carries forward, while a missed year means arguing the same number at the Board of Review in each of the next two years.
- Appeal at both levels. The Board of Review accepts complaints every year regardless of the reassessment cycle, and a reduction at the Assessor does not prevent a further reduction at the Board.
- Classification matters as much as value: Class 5a and 5b property is assessed at 25% of market value and Class 3 apartments at 10%, so a mixed-use building's class code deserves the same scrutiny as its value.
- The state equalization factor is applied to the county total after the Board of Review finishes, so evidence should be framed against the assessed value on the notice, not the equalized value on the tax bill.
Cook County appeal questions
Last verified October 2026 against the assessor, board and statute.
Do I have to appeal to the Assessor before going to the Board of Review?
No. The Board of Review accepts complaints whether or not an Assessor appeal was filed, and it hears appeals every year. Filing at both levels gives two chances at a reduction in the reassessment year.
Is commercial property in Cook County really assessed at 25%?
Yes. Class 5a commercial and Class 5b industrial property is assessed at 25% of market value under the Cook County classification ordinance, and Class 3 apartments are at 10%. A $40 million office building therefore carries a $10 million assessed value before the state equalization factor is applied.
How long do I have to appeal to PTAB?
30 days from the Board of Review's written notice of decision, or 30 days from the Board's transmittal of the township to the Assessor, whichever is later. PTAB treats the deadline as jurisdictional, so a late petition is dismissed.
Can a property manager sign the Board of Review complaint for an LLC owner?
No. Other than individuals appearing for themselves, parties before the Board of Review must be represented by an attorney, including corporations and LLCs. The Assessor's level has no such requirement, although practitioners there must file through SmartFile.
Nearby jurisdictions
Build your Cook County evidence packet in minutes.
The Cook County Board of Review forms, deadlines and exhibit formats are preconfigured. Upload a notice to start.