Don’t Miss Property Tax Assessment Appeal Deadline

d303's TAX APPEAL NECESSITATES TAXPAYER ACTION

With District 303 asking voters to approve a bond referendum that would increase property taxes under the district’s financing estimates, homeowners have a separate issue to consider: Is the assessed value of your property accurate? The referendum will appear on the November 3, 2026, ballot, but some assessment-appeal deadlines arrive before Election Day—and others have already passed. D303 District

For property in Campton Township, the deadline to file a 2026 assessment complaint is Monday, October 26, 2026. Do not assume that date applies to every property with a Campton Hills or St. Charles mailing address. Kane County sets its filing deadlines by township. Kane County Assessments

Understanding the proposed tax increase and checking your assessment are two different tasks. Both begin with reviewing the numbers.

D303 Is Asking Voters to VOTE & PAY

St. Charles Community Unit School District 303 has placed a $282.5 million bond referendum on the November ballot. The borrowing would help fund a $312.5 million facilities package, with the district identifying another $30 million in district resources toward the projects. The proposal includes building repairs, accessibility improvements, classroom and program-space additions, expanded Career and Technical Education space, and a physical education and athletic facility. D303 District

If approved, the proposal would increase the bond-related portion of property taxes under D303’s published estimates.

The district’s calculator provides an example using a $500,000 estimated 2025 property value, an $8,000 general homestead exemption, and no additional exemptions. Under those assumptions, the estimated increase is $645.77 annually, or $53.81 monthly. That is an estimate—not a guaranteed amount for every $500,000 property. Actual payments can vary with assessments, exemptions, district-wide taxable values and other factors. The calculator estimates the increase in D303’s bond-related taxes, not changes in every part of the property-tax bill. D303 District

Residents can review the D303 referendum proposal and project information and use the district’s property-tax impact calculator.

Regardless of your position on the referendum, checking whether your property’s assessment is accurate is a separate step.

First, Check Your Township’s Deadline

There is no single assessment-appeal deadline for all D303 residents or all Kane County property owners. The county’s posted 2026 deadlines include:

Township2026 assessment-complaint deadlineCamptonOctober 26, 2026PlatoOctober 21, 2026St. CharlesJuly 20, 2026 — already passed

These dates come from Kane County’s official filing calendar, checked September 29, 2026. Kane County Assessments

Check the official 2026 filing deadlines for every Kane County township.

Confirm the township for your particular parcel rather than relying on your mailing address or school district. For Campton and Plato properties, waiting until the November referendum vote would mean waiting beyond the posted assessment-complaint deadline. Kane County Assessments

AURORA, BURLINGTON, CAMPTON, HAMPSHIRE, PLATO, KANEVILLE AND VIRGIL......property taxpayers...you still can file!  But your time is limited....

You Are Appealing the Assessment—not the Tax Increase

An assessment complaint challenges the valuation or treatment of your property. It is not the process for opposing a school district’s borrowing proposal or disputing a taxing body’s levy. Kane County expressly explains that the amount of taxes paid, or the percentage increase in value from one year to the next, is not by itself a valid basis for an assessment appeal. Kane County Assessments

For homeowners, the principal grounds include:

• Overvaluation: The property’s equalized assessed value is greater than one-third of its fair cash value.
• Lack of equity: The assessment is higher than those of genuinely comparable properties in the neighborhood.
• Incorrect property information: The assessment relies on inaccurate information, such as incorrect square footage or other physical characteristics. Kane County Assessments

The question is not simply, “Did my taxes increase?”

The question is, “Can I show that my property’s assessment is incorrect or inequitable?”

Review Your Records & Gather Evidence

Start with the Kane County Property Tax Inquiry website, where you can search by parcel number, address or owner name. Review your 2026 assessment notice and request your property record information from the township assessor. Kane County Assessments

Compare the recorded characteristics with the actual property. Check the living area, basement finish, bathrooms, garage and other improvements. For a comparable-property argument, select properties with similar features—not simply properties with lower assessments. The county’s complaint form provides space for those comparisons. Kane County Assessments

For 2026 complaints, the residential form calls for sales from 2023, 2024 and/or 2025 for overvaluation comparisons, and 2026 assessed values for equity comparisons. It calls for at least three comparable properties; an overvaluation claim may also be supported by a complete appraisal report as provided in the county’s rules. Kane County Assessments

Kane County recommends discussing the assessment with the township assessor first. Campton Township’s assessor’s office can be reached at 630-513-5430. Keep the filing deadline in view while those discussions are taking place. Kane County Assessments

the Official Form for Contesting Your Assessment

Homeowners can obtain the county’s instructions and forms here:

Kane County Assessment Complaints: Instructions and Forms

The direct link to the current residential form is:

Download the Official 2026 Residential/Farm Assessment Complaint Form — PDF

This is the county’s two-page complaint form. Complete the required sections, select the grounds for your complaint, sign it, and follow the instructions for your evidence and requested assessment. The county also provides separate forms for commercial and industrial properties on its assessment-complaints page. Kane County Assessments

Important: The Initial Complaint Must Be Filed on Paper

Do not mistake the electronic evidence portal for an online appeal application.

Kane County states that the initial assessment complaint must be submitted on paper by U.S. Mail, private courier or in person. The evidence portal cannot be used to make that initial filing. Kane County Assessments

Submit the complaint to:

Kane County Board of Review
719 S. Batavia Avenue, Building C
Geneva, Illinois 60134
630-208-3818 Kane County Assessments

The county generally treats a properly mailed U.S. Mail submission as filed on its postmark date, subject to its published requirements. Retain a complete copy of your submission and proof of mailing or delivery. Kane County Assessments

Supporting evidence may accompany the complaint. For a complaint already filed, the county also provides a 14-day electronic evidence-submission period after the township’s filing deadline. That additional evidence period does not give you 14 extra days to file the initial complaint. Kane County Assessments

Read the county’s electronic evidence-submission instructions.

Property owners should also note that the complaint form requires corporate owners and taxpayers, including LLCs, to be represented by an Illinois-licensed attorney. Kane County Assessments

Don’t Wait for the Next Tax Bill

The 2026 assessment year applies to property taxes payable in 2027. Kane County warns that waiting until the tax bill arrives is generally too late to begin the ordinary Board of Review assessment-complaint process for that year. Kane County Assessments

The D303 referendum and your property assessment deserve separate consideration. Read the proposal and its estimated tax impact. Review your property records. Compare the assessment with appropriate evidence. And when the evidence supports a complaint, submit it by the deadline that applies to your parcel.

For Campton Township, that deadline is October 26, 2026. For Plato Township, it is October 21, 2026. Kane County Assessments

Check your township’s deadline and get the official complaint form and instructions before deciding your next step.

This article provides general information, not advice about a particular property or appeal. Dates, forms and estimates were checked against the linked official sources on September 29, 2026.