When is the deadline to appeal a Downers Grove property assessment?
November 2, 2026. Downers Grove Township published its 2026 assessments on October 1, which started a 30-day clock. DuPage County now requires all appeals to be filed electronically, as paper and mailed appeals are no longer accepted.
Your 2026 assessment posted October 1. You have until November 2 to do something about it, and a few things about this process catch people off guard every year.
DuPage Went Online Only
Beginning in 2026, the DuPage County Board of Review requires every appeal to be filed electronically. Paper forms are gone. Mailed and emailed appeals are not accepted.
If you appealed in a past year and remember printing a form and driving it to Wheaton, that is no longer how this works.
Know Which Year You Are Appealing
Illinois bills in arrears, which makes this confusing.
The number published October 1 is your 2026 assessment. It determines the bill you pay in 2027. The bill you paid this year was tax year 2025, assessed last year. You are appealing the new number, not the one you already paid.
The Equalization Factor Is Not a Tax Increase
This year's assessments include a Supervisor of Assessments equalization factor of 1.0635. Plenty of people will see that and assume their taxes are going up 6.35%.
That is not what it does.
Your assessed value determines your share of the total tax burden. The size of that burden is set separately, when your taxing bodies pass their budgets. Because the factor applies uniformly to every property in the township, it does not change your proportionate share. Your bill rises when the districts that tax you levy more.
An Informal Review Is Not an Appeal
This is where people get into trouble.
The Township encourages you to contact the Assessor's office first and request an informal review. That is good advice. A deputy assessor can sometimes resolve things at the township level and save you a trip to Wheaton, and contacting them does not waive your right to appeal.
But two things are true at once. An informal review is not a filing with the Board of Review. And the Board's rules state the filing period is not extended while you discuss your assessment with the Township Assessor.
The clock runs either way. With four weeks left, if you want to try the informal route, start now.
Your 2026 Assessment Is Built on 2023, 2024, and 2025 Sales
This trips up more appeals than anything else.
Illinois uses three years of valid sales preceding the assessment year, with a valuation date of January 1. So your 2026 number reflects sales from 2023, 2024, and 2025, weighted toward the more recent years. It does not reflect what happened in the market this year.
That means a 2026 sale is weak evidence. Pull a comparable that closed in March and the Board will give it little weight, because it sits outside the window the assessment was built on.
It also explains why an assessment can feel out of step with what you see around you. If prices climbed this year, your assessment has not caught up. If your area softened recently, the assessment may still be carrying stronger 2023 and 2024 numbers. That second situation is the one worth appealing.
What Actually Supports an Appeal
You are appealing the assessed value, not your tax bill. The Board has no authority to change a bill directly.
Illinois assesses residential property at roughly one third of market value, so your assessment implies an opinion of what your home was worth on January 1, 2026. Two kinds of evidence challenge it.
Comparable sales from the 2023 to 2025 window. If the implied market value sits well above what similar homes actually traded for, that is your argument.
Comparable assessments. If your number is out of line with nearby homes of similar size, age, and condition, that is a uniformity argument.
On finding sales data, the Township's own appeal guide points homeowners three places: the Assessor's Parcel Search, the MLS or a realtor, or an appraisal.
The Board asks that filings use its prescribed forms and comparison grids. Appraisal reports are accepted up to ten days after the deadline.
Key Dates
- October 1: Assessments published and live on Parcel Search
- November 2: Deadline to file with the DuPage County Board of Review
Deadlines are not countywide. Each township publishes on its own date and its own 30-day clock runs from there. Bloomingdale published September 25, with an October 26 deadline. Your neighbor's date may not be yours.
Where to Start
Go to dgtownship.com, select Assessor, then Parcel Search. Look up your property by address or 10-digit parcel number. The same section is where you request an informal review.
Multiply your assessed value by three. If that number looks high against what homes like yours sold for in 2023 through 2025, you have something worth pursuing.
A deputy assessor attends the Board of Review hearing, so your assessment gets defended by the office that set it. Decisions are generally mailed the following March, and can be appealed to the Illinois Property Tax Appeal Board within 30 days.
The Township Assessor's office is at 4340 Prince Street, 630-719-6630.
Frequently Asked Questions
What is the 2026 appeal deadline in Downers Grove Township?
November 2, 2026, which is 30 days after the October 1 publication date. The Board of Review cannot accept late filings.
What years of sales does my 2026 assessment use?
Sales from 2023, 2024, and 2025, with more weight on the recent years. The valuation date is January 1, 2026, so sales from this year generally carry little weight in an appeal.
Which tax bill does this assessment affect?
The one you pay in 2027. Illinois bills in arrears, so the 2026 assessment published this month determines next year's bill, not the one you already paid this year.
Does the 1.0635 equalization factor mean my taxes go up 6.35%?
No. It applies uniformly to all properties, so it does not change your proportionate share of the tax burden.
Is an informal review the same as filing an appeal?
No. It is handled at the township level and is not a filing with the Board of Review. The 30-day window keeps running while one is pending.
An appeal lives or dies on comparable sales, which is exactly what the Township's own guide tells homeowners to ask a realtor for. If you want a straight read on what homes like yours sold for in the years that actually count, call or text Rob Brannigan at 847.609.0570 or visit robbrannigan.com. Happy to tell you whether you have a case before you spend time on the filing.
Additional Resources
- Downers Grove Township Assessor
- DuPage County Board of Review
- DuPage County Property Tax Bills: What Homeowners Need to Know
- North vs. South Downers Grove: What 360 Home Sales Show
- Youtube Video on Property Assessments
Written by Rob Brannigan (IL License #475.164040), RENE + SRS. Lifelong Downers Grove resident. Data-driven guidance for sellers and buyers in Downers Grove and surrounding communities.
