Illinois Property Tax Appeal Guides
Browse source-reviewed property tax appeal guides for Illinois. County deadlines, filing methods, and available records can differ by county and tax year.
Each published guide identifies the public sources used for its deadline and filing summary. Confirm current requirements with the official filing authority before submitting anything.
How Illinois assessment appeals generally work (state framework reviewed 2026-08-02 from official Illinois sources): Local assessing officials determine fair cash value. Property is generally assessed at 33 1/3% of fair cash value outside a county authorized to classify property, while Cook County uses classification and class-specific assessment levels, so a single statewide parcel ratio is not accurate. A property owner may first discuss the assessment with the local assessor, but a written complaint to the County Board of Review is required before a further appeal to the Illinois Property Tax Appeal Board or a tax-objection complaint in Circuit Court. Final Property Tax Appeal Board decisions are subject to judicial review under the applicable statute.
Illinois deadline framework: The County Board of Review sets and publishes the local complaint period, form, and filing deadline; there is no single safe statewide first-appeal date. An appeal to the Property Tax Appeal Board is generally due within 30 days after the written Board of Review decision or another statutorily authorized trigger. Circuit Court and later judicial-review paths have distinct payment, objection, and filing requirements.
Local variation in Illinois: Township, multi-township, and county assessment structures vary, and County Boards of Review control local forms, calendars, evidence rules, and hearings. Cook County classification and procedures differ materially from the general statewide framework. Farm, commercial, industrial, and exempt property can require different forms and proof.
Before relying on a date: Resolve the county, township or assessment district, property class, assessment year, publication and notice history, and any assessor review, then verify the local Board of Review's current complaint form and receipt deadline, final decision date, Property Tax Appeal Board filing instructions, and any Circuit Court payment or objection prerequisites.
State source: Illinois Department of Revenue, Assessment Appeals — Property Tax, https://tax.illinois.gov/localgovernments/property/appeals.html. Reviewed 2026-08-02.
State source: Illinois Department of Revenue, Illinois Property Tax Code, https://tax.illinois.gov/content/dam/soi/en/web/tax/research/publications/pubs/documents/pub-136.pdf. Reviewed 2026-08-02.
State source: Illinois Property Tax Appeal Board, Filing Your Appeal, https://ptab.illinois.gov/filing.html. Reviewed 2026-08-02.
Cook County: 2026 deadline guidance is Township-specific 2026 filing dates; check the live CCAO calendar and your assessment notice. Guide: https://fairpath.app/property-tax-appeal/illinois/cook-county
DuPage County: 2026 deadline guidance is Wayne Township: September 28, 2026; other township dates remain unpublished. Guide: https://fairpath.app/property-tax-appeal/illinois/dupage-county
Kane County: 2026 deadline guidance is Township-specific 2026 deadline; published dates are live while remaining townships show TBD. Guide: https://fairpath.app/property-tax-appeal/illinois/kane-county
Macon County: 2026 deadline guidance is 2026 deadline not yet posted; confirm the publication-based window with the Supervisor of Assessments. Guide: https://fairpath.app/property-tax-appeal/illinois/macon-county
Peoria County: 2026 deadline guidance is Township-specific 2026 filing schedule expected in fall 2026. Guide: https://fairpath.app/property-tax-appeal/illinois/peoria-county
Rock Island County: 2026 deadline guidance is Thirty days after the 2026 assessment publication date; the county has not yet posted a closing date. Guide: https://fairpath.app/property-tax-appeal/illinois/rock-island-county
Stephenson County: 2026 deadline guidance is 2026 date still unpublished; the Sept 10, 2026 default has passed with no confirmed list. Guide: https://fairpath.app/property-tax-appeal/illinois/stephenson-county
Will County: 2026 deadline guidance is August 12 through September 14, 2026. Guide: https://fairpath.app/property-tax-appeal/illinois/will-county
Winnebago County: 2026 deadline guidance is 2026 closed: September 4 (Group 1) or September 5 (Group 2). Guide: https://fairpath.app/property-tax-appeal/illinois/winnebago-county
Source: Cook County Assessor's Office, Assessment & Appeal Calendar and Deadlines, https://www.cookcountyassessoril.gov/assessment-calendar-and-deadlines. Reviewed 2026-09-20.
Source: Cook County Assessor's Office, Cook County Assessor Advanced Property Search, https://www.cookcountyassessoril.gov/advanced-search. Reviewed 2026-08-09.
Source: Cook County Assessor's Office, Official Appeal Rules of the Cook County Assessor for 2026, https://www.cookcountyassessoril.gov/official-appeal-rules-cook-county-assessor. Reviewed 2026-08-09.
Source: Cook County Assessor's Office, Online Appeals, https://www.cookcountyassessoril.gov/online-appeals. Reviewed 2026-08-09.
Source: Cook County Assessor's Office, Residential Appeals, https://www.cookcountyassessoril.gov/residential-appeals. Reviewed 2026-08-09.
Source: Cook County Board of Review, Residential Assessment Appeals, https://www.cookcountyboardofreview.com/assessment-appeals/residential. Reviewed 2026-08-09.
Source: DuPage County GIS, How to Use the DuPage Parcel Viewer, https://videos.dupagecounty.gov/GIS/HowToUseParcelViewer.pdf. Reviewed 2026-07-15.
Source: DuPage County GIS, Real Estate Database Information, https://www.dupagecounty.gov/GIS/Documents/DuPageCountyRealEstateDatabaseInfo.pdf. Reviewed 2026-07-15.
Source: DuPage County Supervisor of Assessments, Property Assessment Appeal Process, https://www.dupagecounty.gov/government/departments/supervisor_of_assessments/appeal_process.php. Reviewed 2026-08-30.
Source: DuPage County Supervisor of Assessments, Township Assessment Publication and Filing Deadlines, https://www.dupagecounty.gov/government/departments/supervisor_of_assessments/assessment_status.php. Reviewed 2026-08-30.
Source: Illinois Department of Revenue, Assessment Appeals, https://tax.illinois.gov/localgovernments/property/appeals.html. Reviewed 2026-07-29.
Source: Illinois Department of Revenue, Illinois Property Tax System, https://tax.illinois.gov/content/dam/soi/en/web/tax/research/publications/documents/localgovernment/ptax-1004.pdf. Reviewed 2026-07-16.
Source: Illinois Property Tax Appeal Board, Getting Started with a PTAB Appeal, https://www.ptab.illinois.gov/getStarted.html. Reviewed 2026-08-09.
Source: Kane County Assessment Office, 2026 Township Filing Deadlines, https://assessments.kanecountyil.gov/Pages/Deadline.aspx. Reviewed 2026-07-29.
Source: Kane County Board of Review, 2026 Residential and Farm Assessment Complaint, https://assessments.kanecountyil.gov/Documents/Complaint%20Forms/ResidentialFarm.pdf. Reviewed 2026-07-29.
Source: Kane County Board of Review, 2026 Rules and Procedures, https://assessments.kanecountyil.gov/Documents/Rules.pdf. Reviewed 2026-07-29.
Source: Kane County Board of Review, Assessment Complaints, https://assessments.kanecountyil.gov/Pages/Assessment-Complaints.aspx. Reviewed 2026-07-29.
Source: Kane County Board of Review, Electronic Evidence Submission, https://assessments.kanecountyil.gov/Pages/Evidence.aspx. Reviewed 2026-07-29.
Source: Macon County Government, Macon County Board of Review, https://maconcounty.illinois.gov/departments/county-board/macon-county-board-appointments/board-of-review/. Reviewed 2026-07-16.
Source: Macon County Government, Supervisor of Assessments and Complaint Guidance, https://maconcounty.illinois.gov/departments/supervisor-of-assessments/. Reviewed 2026-07-16.
Source: Peoria County Government, Assessment Complaints and County Packets, https://www.peoriacounty.gov/507/Assessment-Complaints. Reviewed 2026-07-16.
Source: Peoria County Government, Peoria County Board of Review, https://www.peoriacounty.gov/686/Board-of-Review. Reviewed 2026-07-16.
Source: Peoria County Government, Peoria County Submission Resources, https://www.peoriacounty.gov/146/Submit. Reviewed 2026-07-16.
Source: Rock Island County Government, Appealing an Assessment: Seven Steps, https://www.rockislandcountyil.gov/180/Appealing-an-Assessment. Reviewed 2026-07-16.
Source: Rock Island County Government, Board of Review Office and Complaint Window, https://rockislandcountyil.gov/175/Board-of-Review-Office. Reviewed 2026-07-16.
Source: Rock Island County Government, Rock Island County Board of Review Rules, https://www.rockislandcountyil.gov/181/Board-of-Review-Rules-PDF. Reviewed 2026-07-16.
Source: Stephenson County Board of Review, 2025 Stephenson County Board of Review Rules, https://stephensoncountyil.gov/Document_Center/Department/County%20Assessment%20Office/2025%20Stephenson%20County%20Board%20of%20Review%20Rules.pdf. Reviewed 2026-07-29.
Source: Stephenson County Chief County Assessment Office, Assessment Complaint Forms and Publications, https://stephensoncountyil.gov/departments/county_assessment_office/forms___publications/index.php. Reviewed 2026-07-29.
Source: Stephenson County, Illinois, Board of Review, https://stephensoncountyil.gov/departments/county_assessment_office/board_of_review/index.php. Reviewed 2026-07-29.
Source: Stephenson County, Illinois, County Assessment Office, https://stephensoncountyil.gov/departments/county_assessment_office/index.php. Reviewed 2026-07-29.
Source: Will County Board of Review, 2026 Board of Review Rules and Procedures, https://willcountysoa.com/Content/pdf/2026_BORRulesAndProcedures.pdf. Reviewed 2026-07-15.
Source: Will County Supervisor of Assessments, Board of Review Complaint Downloads, https://borappeals.willcountysoa.com/downloads.aspx. Reviewed 2026-07-15.
Source: Will County Supervisor of Assessments, Board of Review Complaint Portal, https://borappeals.willcountysoa.com/Home. Reviewed 2026-09-13.
Source: Will County Supervisor of Assessments, Will County Board of Review Complaint FAQ, https://borcomplaints.willcountysoa.com/FAQ. Reviewed 2026-09-13.
Source: Winnebago County, Supervisor of Assessments, https://wincoil.gov/departments/supervisor-of-assessments/. Reviewed 2026-07-29.
Source: Winnebago County Supervisor of Assessments, Board of Review, https://wincoil.gov/departments/supervisor-of-assessments/board-of-review. Reviewed 2026-07-29.
Source: Winnebago County Supervisor of Assessments, Property Assessment Frequently Asked Questions, https://wincoil.gov/departments/supervisor-of-assessments/faqs. Reviewed 2026-07-29.
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