How to Appeal Property Taxes in Kane County, Illinois (2026 Guide)

Direct answer: In Kane County, 2026 assessment complaints are due 30 calendar days after your township’s assessment-change publication date. As of July 27, 2026, the current deadline is today, July 27, 2026, for Blackberry Township; already-set upcoming deadlines are August 17, 2026 for Big Rock and Geneva and August 24, 2026 for Sugar Grove. File the paper Residential/Farm Assessment Complaint for 2026 with the Kane County Board of Review, 719 Batavia Avenue, Building C, Geneva, IL 60134-3000—not by email and not through the evidence portal.

How assessments work in Kane County

Kane County is not a single countywide reassessment deadline system. Assessments move township by township. Each of Kane County’s 16 elected township assessors develops the initial property valuations; the County Supervisor of Assessments then equalizes assessments for uniformity, and the Kane County Board of Review hears formal complaints.

For most homes, the target assessment is 33.33% of fair cash value as of January 1, 2026, using sales from 2023, 2024, and 2025. The county’s 2026 Board of Review rules say the 2026 valuation date is January 1, 2026, and that sales outside the 2023-2025 study period require an explanation of why they best represent value.

The 2026 progress report shows township equalization factors and appeal deadlines. Published 2026 residential deadlines so far are: Dundee: July 9, 2026; Saint Charles: July 20, 2026; Blackberry: July 27, 2026; Big Rock: August 17, 2026; Geneva: August 17, 2026; Sugar Grove: August 24, 2026. Aurora, Batavia, Burlington, Campton, Elgin, Hampshire, Kaneville, Plato, Rutland, and Virgil were still listed with no deadline date in the county progress report at the time of this guide.

Whether you should appeal

Appeal if your assessment is wrong for one of Kane County’s accepted reasons—not simply because your tax bill went up. The Board recognizes these bases: overvaluation, inequity compared with similar properties, incorrect physical data such as square footage or lot size, or eligibility for a preferential assessment.

Start with the math. Divide your total equalized assessed value by 0.3333 to estimate the market value implied by the assessment. If the assessment shows a $480,000 market value but comparable homes in your subdivision sold for $430,000 to $445,000 in 2023-2025, you may have an overvaluation case. For an equity case, compare your 2026 assessed value per square foot to similar homes near you, not just sale prices.

Do not argue “my taxes are too high,” “my assessment increased too much,” or “the tax rate is unfair.” Kane County’s own FAQ and Board rules say tax amount, tax-rate changes, and percentage change from last year are not valid assessment-complaint bases.

Also check exemptions before or alongside an appeal. Kane County’s exemption page says homestead exemptions reduce taxable value before tax is calculated. The online exemption portal supports General Homestead, Senior Homestead, Persons with Disabilities, Veterans with Disabilities, Veterans annual renewal, and Returning Veterans exemptions. The Senior Freeze is especially important in 2026: the maximum household income rises to $75,000 for 2026 payable 2027, and the county emphasizes that the freeze limits the assessment, not the tax bill itself.

Step-by-step how to file

1. Find your township and deadline. Use your assessment notice, tax bill, or the county property search to identify your township and PIN. The deadline is township-specific and is 30 calendar days after publication.

2. Talk to your township assessor immediately. Kane County strongly encourages this, but discussions do not extend the Board of Review deadline. If today is your deadline, file first and keep talking afterward.

3. Use the correct form. Most homeowners use Residential/Farm Assessment Complaint for 2026. Condo or common-interest associations use the Association Assessment Complaint Form. If one property has multiple PINs, attach the Multi-Parcel Addendum.

4. Pick your hearing option on the form. A Standard Hearing means you appear by Zoom telephone or video. A Streamlined Hearing means the Board decides from written evidence submitted by you and the assessor, without your appearance.

5. Attach evidence or preserve your right to add it. For overvaluation, Kane County asks for at least three sales comparables from 2023, 2024, and/or 2025. For equity, use 2026 assessed-value comparables. If you bought the home on or after January 1, 2023, disclose the purchase price and date and include relevant sale documents.

6. File on paper. Kane County’s evidence page is explicit: the portal cannot be used for the initial complaint. Initial complaints must be filed by United States Mail, private courier, or in person at the Board of Review office in Geneva. Faxed and emailed complaint forms are not accepted. Mail or deliver to: Kane County Board of Review, 719 Batavia Avenue, Building C, Geneva, Illinois 60134-3000. USPS filings count by postmark; private courier filings count by the shipper’s tracking-label date, but only if sent to the Board’s Geneva office.

7. Use the evidence portal only after filing. The Electronic Evidence Filing Portal is only for evidence in an already-filed complaint, and it remains open for 14 calendar days after that township’s final filing deadline. There is no county filing fee listed in the 2026 rules or complaint form; plan only for postage, courier, copies, or optional appraisal costs.

What happens after

The appeal authority is the Kane County Board of Review, a three-member board. The 2026 rules list Timothy J. Sullivan as Chairman, Constantine “Dino” Konstans as Member, Michael E. Madziarek as Member, and Mark D. Armstrong as Clerk.

If you request a standard hearing, Kane County conducts assessment-complaint hearings by Zoom teleconference or Zoom video conference. The county says hearings are scheduled in 15-minute intervals. You present first, answer Board questions, then the township assessor or representative may present and answer questions. Each side may make closing or rebuttal remarks. The Board usually gives an oral decision after the hearing closes, but the official decision is the later written decision of the full Board.

If you request a streamlined hearing, there is no live appearance. The Board reviews written evidence from you and the assessor. Kane County says official findings are mailed to complainants and respondents after all standard and streamlined hearings are completed; no final decisions are released before then.

If you disagree with the written Board of Review decision, the next appeal is to the Illinois Property Tax Appeal Board. PTAB says the petition must be filed within 30 days of the county board of review’s written decision.

Local tips

Kane County publishes useful township-level progress data. The 2026 projected equalization factors were all above 1.04 in the posted progress report, so many homeowners will see upward adjustment even before individual property changes. That does not itself prove overassessment; it tells you to compare your implied value against actual 2023-2025 sales.

Use the county’s sales search and property search before paying for help. For a strong residential case, choose nearby homes in the same subdivision when possible, similar in living area, age, style, quality, condition, basement finish, garage spaces, and lot size. The Board’s rules say farther-away or different-subdivision comps can be considered, but you carry the burden of proving they are the best available.

Kane County does not publish an easy homeowner “success rate” or median reduction statistic in the official appeal pages reviewed for this guide. Do not rely on a tax-appeal company’s advertised average unless it separates Kane County, residential-only, current-year Board of Review results.

A realistic savings example: Kane County’s exemption page says tax rates generally range from about 6.50% to 11.25%, with a median rate of 9.00%; the official 2025 payable 2026 tax-code booklet also shows individual rates, such as DU026 at 7.123204%. Suppose a home is assessed at $150,000 EAV, implying roughly $450,000 market value. You prove the correct market value is $420,000, so the correct EAV is about $140,000. The EAV reduction is $10,000. At the county median 9.00% rate, that is about $900 in one-year tax savings. At the DU026 rate, it would be about $712. Your own savings equals your EAV reduction multiplied by your exact tax-code rate on the bill.