Every few years, a letter arrives in Chicago-area mailboxes that tends to cause immediate stress: the Notice of Proposed Assessment. For many homeowners, it is the first indication that the Cook County Assessor has re-evaluated their property — and that their tax bill may be about to change significantly. What that letter means, what you are legally entitled to do about it, and how the entire reassessment system works is something the Camille Canales Group walks clients through regularly. This guide explains all of it.
Quick answer: Cook County reassesses residential properties on a rotating three-year cycle. Chicago was reassessed in 2024; the next Chicago reassessment is 2027. When you receive a Notice of Proposed Assessment, you have 30 days to appeal. That window is critical and not extendable.
The Triennial Reassessment Cycle Explained
Cook County is one of the most complex property tax jurisdictions in the United States, home to more than 1.8 million parcels. To manage reassessment efficiently, the county is divided into three geographic regions, each of which is reassessed once every three years. The regions rotate through the cycle so that roughly one-third of properties are reassessed each year.
This system is called the triennial reassessment, and it means that your property will be formally re-examined approximately once every three years — not every year. In between reassessments, your assessed value carries forward with only modest adjustments.
Triennial Region | Geographic Area | Recent Reassessment Years | Next Reassessment |
|---|---|---|---|
Triennial 1 | North & Northwest Suburbs | 2019, 2022, 2025 | 2028 |
Triennial 2 | South Suburbs | 2020, 2023, 2026 | 2029 |
Triennial 3 | City of Chicago | 2021, 2024, 2027 | 2027 |
For Chicago homeowners: 2024 was the most recent reassessment year. Notices went out throughout 2024, and the resulting assessments are now reflected in your current tax bills. The next full Chicago reassessment will occur in 2027 — but that does not mean you cannot appeal in the meantime. You can. More on that shortly.
What "Reassessment" Actually Means for Your Tax Bill
The word "reassessment" conjures images of skyrocketing tax bills, and sometimes that fear is warranted. But it is important to understand the mechanics of what actually changes — and what does not — when the Assessor reviews your property.
Here is how the calculation works:
Step 1: Estimated Market Value
The Assessor estimates what your property would sell for on the open market. This is based on recent comparable sales in your neighborhood, property characteristics from the property record card (square footage, bed/bath count, lot size, construction type), and mass appraisal models.
Step 2: Assessed Value (10%)
Illinois law sets the assessment level for residential property at 10% of estimated market value. So if your home is estimated at $500,000, your Assessed Value (AV) would be $50,000. This is the number printed on your Notice of Proposed Assessment.
Step 3: State Equalization Factor (Multiplier)
The Illinois Department of Revenue applies a State Equalization Factor — also called the multiplier — to bring Cook County assessments to the statutory one-third of market value. This factor fluctuates annually but has historically been approximately 2.9 to 3.0 for Cook County. Multiplying your AV by the equalization factor gives you the Equalized Assessed Value (EAV).
Step 4: Exemptions
Eligible homeowners subtract exemptions from their EAV. The most common is the Homeowner Exemption, which reduces EAV by $10,000. Senior citizens may qualify for an additional $8,000 reduction, plus a Senior Freeze exemption that locks in their EAV. Veterans and persons with disabilities have additional exemptions available.
Step 5: Tax Rate Applied to Net EAV
Your taxing district's composite rate (schools, parks, city, county, transit, etc.) is applied to your net EAV after exemptions. In Chicago, this rate typically ranges from 6% to 9%, depending on your specific location and the taxing bodies that cover your address.
Illustrative example: Home estimated at $500,000 → AV = $50,000 → EAV at ×2.9 = $145,000 → minus Homeowner Exemption $10,000 = net EAV $135,000 → at 7.8% tax rate = approximately $10,530/year in property taxes.
Reassessment Does Not Automatically Mean Higher Taxes
This is one of the most important nuances for homeowners to understand. A reassessment that raises your assessed value does not automatically translate to a proportionally higher tax bill. Here is why:
Tax rates adjust to levy demands. Taxing bodies (school districts, the city, etc.) set annual levy amounts — the total dollars they need to collect. Those levies are divided across all the EAV in the district. If all property values in your district go up by 15%, the effective tax rate tends to drop, partially offsetting the higher EAV. Your individual bill increase depends on whether your assessed value rose more or less than the average in your district.
However, reassessment can still hurt you in real terms if your property was assessed significantly below market value previously and is now being "caught up" — or if your value rose faster than your neighbors' values in the same district. This is exactly the scenario where an appeal can make a meaningful financial difference.
The Timeline: From Notice to New Tax Bill
Understanding when things happen helps you act at the right time. Here is a general timeline for a Chicago homeowner in a reassessment year:
Phase | Typical Timing | What Happens |
|---|---|---|
Notice Mailed | Spring–Summer of reassessment year | Assessor mails Notice of Proposed Assessment to property owner |
Assessor Appeal Window | 30 days from notice date | File appeal at assessor.cookcountyil.gov; Assessor reviews and rules |
Board of Review Window | Township-specific, typically fall | Second appeal level opens; window is separate by township |
Assessment Certified | Late fall/winter | Final assessed values certified by Assessor; multiplier applied |
First Installment Due | March 1 of following year | 55% of prior year's bill (billed before final rates are set) |
Second Installment Due | Approximately August of following year | Balance of current year's actual bill, incorporating new assessment |
Notice that the new assessed value from a reassessment year does not hit your tax bill until the following year's second installment. This means if your property was reassessed in 2024, the full financial impact appears in your second installment due in August 2025. The first installment (March 2025) would have still been based on your 2023 figures.
What to Do When You Receive a Notice of Proposed Assessment
The notice is not a bill. It is an opportunity. Here is what to do in the days immediately after it arrives:
1. Note the Filing Deadline Immediately
The notice will state the deadline by which you must file an Assessor-level appeal. This is 30 days from the notice date. Write it down. Put it in your calendar. This deadline is firm, and missing it forfeits your Assessor-level appeal opportunity.
2. Find Your PIN and Look Up Your Property Record Card
Your Property Index Number (PIN) is the 14-digit number on the notice. Go to cookcountyassessor.com and pull your property record card. Verify every detail: square footage, number of bedrooms and bathrooms, garage type, lot size, construction type. Errors in the property record card are surprisingly common and can form the basis for a successful appeal.
3. Calculate What the Assessment Implies About Your Property's Value
Take the Assessed Value on the notice and divide by 0.10. That gives you the implied market value the Assessor is using. Compare that number to what you believe your home would sell for today. If the Assessor's implied value exceeds realistic market value — especially if you purchased recently at a lower price — you have a strong basis for appeal.
4. Pull Comparable Sales
Look at recent arm's-length sales (non-distressed, non-family transactions) of properties similar to yours — same property type, similar size, same general neighborhood — that closed within the past 12 months. Ideally within half a mile. If those comparable sales support a lower market value, you have evidence. If you work with a real estate professional, this is exactly the kind of data we can provide.
5. Decide Whether to File an Appeal
If the Assessor's implied value is at or below market value, and the property record card is accurate, you may have limited grounds for appeal. But if the value is inflated, there are errors on the record card, or recent comparable sales tell a different story, filing an appeal is worth the time. The process is free. The upside can be hundreds or even thousands of dollars per year in perpetuity.
Three Statistics Every Chicago Homeowner Should Know
30 Days to Appeal After receiving your Notice of Proposed Assessment, this is your window to file an Assessor-level appeal. | 2027 Next Chicago Reassessment Chicago was last reassessed in 2024. The next triennial reassessment for the City of Chicago is scheduled for 2027. | 10% Assessment Level Illinois law sets the residential assessment level at 10% of estimated market value. Divide your AV by 0.10 to find the implied market value. |
Why the 2024 Chicago Reassessment Matters Right Now
The 2024 Chicago reassessment was one of the most significant in recent memory. Chicago property values rose substantially from 2021 to 2024, and the Assessor's office used that market data to update assessed values across the city. Many homeowners saw their assessed values increase by 20%, 30%, or more.
If you own property in Chicago and received a notice in 2024 but did not appeal — either because you missed the deadline or did not realize you could — your current tax bill reflects those higher assessments. The good news: you can still file a Board of Review appeal during the BOR's open township window, and you will have another full Assessor-level appeal opportunity in 2027 when the next reassessment occurs.
If you purchased your Chicago property after the 2024 reassessment notices went out — particularly if you purchased in late 2024 or in 2025 — your purchase price is powerful evidence. If the Assessor's implied market value (AV ÷ 0.10) is higher than what you actually paid, that is exactly the kind of discrepancy that makes for a successful appeal.
Common Misconceptions About Reassessment
"I can't appeal because it's not a reassessment year."
False. The Board of Review accepts appeals in every year, during each township's annual open window. You do not need to wait for a reassessment to challenge your assessed value.
"Appealing will trigger an audit or increase my assessment."
False. Cook County does not increase assessments in response to appeals. The Assessor can only maintain or reduce the assessment you challenged. There is no punitive mechanism for filing an appeal in good faith.
"If the market went up, I have no grounds to appeal."
Not necessarily. The question is not whether the market rose — it is whether your assessment is accurate and equitable. If comparable properties are assessed lower relative to their market value, you may have a uniformity argument even if values generally increased.
"I need a lawyer to appeal."
Not for the Assessor or Board of Review levels. These are designed to be accessible to property owners representing themselves. A tax attorney or consultant can be valuable for complex cases, larger properties, or PTAB appeals — but thousands of homeowners successfully appeal on their own every year.
The Bottom Line on Reassessment
Reassessment is not something that happens to you — it is something you can participate in. The Cook County appeal system is specifically designed to give property owners a voice in the valuation process. Understanding the cycle, knowing your deadlines, and checking your property record card for accuracy are the first steps. Filing an appeal when the evidence supports it can result in meaningful, permanent savings on your annual tax bill.
If you recently purchased a Chicago property or received a notice that gave you pause, talk to the Camille Canales Group. We work with buyers and owners across Chicago's neighborhoods and can help you evaluate whether an appeal makes sense in your specific situation.
Continue Reading
This post is part of the Camille Canales Group's ongoing property tax education series for Chicago homeowners:
→ Chicago Property Taxes Explained: Key Dates, Tools, and Expert Help
→ How to Appeal Your Cook County Property Tax Assessment: A Step-by-Step Guide
→ The Property Tax Appeal Checklist for Chicago Homeowners
→ What a Successful Property Tax Appeal Actually Looks Like: A Logan Square Case Study
→ Property Tax Appeal FAQ: Every Question Chicago Homeowners Ask Us
Have Questions About Your Cook County Assessment?
The Camille Canales Group helps Chicago buyers and homeowners navigate property taxes, appeals, and everything in between. We are happy to pull comparable sales data or walk you through your property record card at no charge.
Camille Canales Group | Compass | ccg-chicago.com | 773-377-9200. This article is for informational purposes only and does not constitute legal or tax advice. Cook County assessment timelines and deadlines are subject to change; verify current dates at assessor.cookcountyil.gov and borc.cookcountyil.gov. Consult a qualified tax attorney or advisor regarding your specific situation.
