The short answer
Cook County is reassessing the south and west suburbs in 2026, with notices mailing township by township from late April through the summer. A higher assessment does not automatically mean a higher tax bill, because bills depend on how your value moved relative to your neighbors, the levies local governments set, your exemptions, and your appeals. Owners who plan to stay should appeal during their township window; owners already strained by taxes, repairs, or timing may do better selling before the new values reach the 2027 bills.
Every three years, the Cook County Assessor revalues one-third of the county, and in 2026 it is the south and west suburbs' turn. For homeowners in Harvey, Oak Lawn, Cicero, Tinley Park, Chicago Heights, Berwyn, Oak Park, and dozens of other communities, the reassessment notice arriving this spring and summer is the first official signal of what the next three years of property taxes might look like. After what happened in the last two cycles, plenty of owners are opening those envelopes with a knot in their stomach.
This guide covers which townships are affected, when the new values actually reach tax bills, what the prior cycles suggest, how to appeal, and how to decide between appealing and selling. The most important sentence in it is this one: a reassessment notice is not a tax bill, and a higher assessment does not automatically mean a higher bill. What you do during the appeal window, and what every other owner in your township does, shapes the outcome.
Which Cook County townships are reassessed in 2026
The 2026 reassessment covers the south and west suburban townships of Cook County: Berwyn, Bloom, Bremen, Calumet, Cicero, Lemont, Lyons, Oak Park, Orland, Palos, Proviso, Rich, River Forest, Riverside, Stickney, Thornton, and Worth, according to appeal-industry roundups from Kensington Research and O'Connor. That list reaches from Bloom, Rich, and Thornton townships along the south end of Cook County to Proviso, Oak Park, and River Forest on the west side, taking in communities such as Chicago Heights, Park Forest, Harvey, Dolton, Calumet City, Tinley Park, Orland Park, Oak Lawn, Palos Hills, Berwyn, Cicero, Maywood, and Bellwood.
Notices are mailed township by township as the Assessor's office finishes each one. Per the Cook County Assessor's assessment calendar, the 2026 cycle opened with River Forest notices on April 20, 2026 and Riverside on April 24, 2026, with the remaining south and west townships following from May through the summer. Each mailing opens that township's appeal window, so the date on your notice matters more than any countywide date you read about. Chicago itself and the north suburbs are not part of the 2026 cycle; the city was reassessed in 2024 and the north suburbs in 2025.
When will the 2026 reassessment hit my tax bill
The new 2026 values generally first appear on the second installment tax bill issued in 2027, because Cook County bills a year in arrears, and they then shape bills into 2028 and 2029 until the next reassessment of these townships. Kensington's 2026 south district guide makes the same point from the appeal side: reductions won on the 2026 assessment begin appearing on the 2027 second installment and can carry through 2028 and 2029.
Exact billing dates are not fixed in advance. The Cook County Treasurer sets the billing schedule each year, and recent years have seen second installment bills move around the calendar, so check the Assessor's notice and tax bill explainer and the Treasurer's current schedule rather than planning around an assumed due date. The practical takeaway for 2026 sellers and stayers alike: there is a lag of roughly a year between the notice in your mailbox and the bill that reflects it, and that lag is your planning window.
How much will my property taxes go up after reassessment
There is no automatic increase, and that point deserves to be repeated before any statistics: reassessment redistributes the tax burden, it does not set it. Your bill depends on four moving parts. First, how your new assessment compares with the average change in your township, because a below-average increase can actually lower your share. Second, the levies that school districts, municipalities, and other local governments adopt, which set the total amount collected. Third, your exemptions, such as the homeowner, senior, and senior freeze exemptions, which shield part of your value. Fourth, appeals, both yours and your neighbors'. The Assessor's own explainer on notices and bills walks through this relationship.
That said, the recent history in Cook County explains why owners take these notices seriously. In the 2023 reassessment of these same south and west suburban townships, appeal firm O'Connor reports that some neighborhoods saw assessment increases of over 700 percent, alongside documented errors such as vacant lots valued as if homes stood on them. After the separate 2024 City of Chicago reassessment, the same source and the National Law Review press release describe 2025 bills in the city rising about 16 percent for the average Chicago homeowner, with the West Garfield Park neighborhood on Chicago's West Side seeing average increases around 133 percent. Those figures are prior-cycle context from earlier reassessments of other districts and prior years, not projections of what 2026 will do to any south suburban bill, but they are the reason county officials themselves urge owners to review and appeal.
What happened in 2023, and why it still matters
The 2023 south suburban reassessment is the cautionary tale hanging over the 2026 cycle, because it was the last time these townships were revalued and it went badly for many owners. Beyond the headline assessment jumps, the cycle surfaced data problems, misclassified parcels, and bill shocks that landed hardest on working-class south suburban communities where home values had been rising quickly off a low base. The same O'Connor analysis notes a longer arc behind those events: a Cook County Treasurer study found county property taxes up 182 percent over the past 30 years, far ahead of inflation, driven by levies, pensions, and shifting burdens.
Two lessons carry forward. First, check the notice for factual errors immediately: square footage, lot description, building class, and condition. The 2023 cycle showed that mistakes happen at scale, and an error caught in the appeal window is far cheaper than one corrected after bills issue. Second, do not assume the first number is the final number. The county's own officials, including the Assessor, Treasurer, and Board of Review, have publicly encouraged owners to appeal, and the two-stage appeal structure exists precisely because initial mass valuations are imperfect. Our Illinois property tax statistics guide collects the longer-run numbers if you want the full picture.
Should I appeal or sell after my reassessment
Appeal if you intend to keep the home; consider selling when the math of staying no longer works even with a successful appeal. The two moves are not mutually exclusive, since an appeal costs nothing and a pending or won appeal does not block a sale, but they serve different goals. Here is the framework we walk south suburban owners through:
- Appeal and hold when you can afford the current bill, the home fits your life, and the notice looks high relative to comparable homes nearby. A reduction generally lasts the rest of the three-year cycle, so the payoff compounds across 2027, 2028, and 2029 bills.
- Appeal and still plan a sale when you expect to move within a year or two anyway. A lower assessment helps marketability, because buyers in the south and west suburbs increasingly ask about the tax bill before the bedroom count.
- Sell sooner when taxes are already delinquent, the home needs repairs you cannot fund, the bill is unaffordable on a fixed income even with exemptions, or you inherited the property and no one wants to manage an appeal cycle from out of state. Selling before the 2027 bills land converts uncertainty into a closed number.
For a deeper side-by-side on that decision, see our guide to the Cook County appeal versus selling decision and our 2026 commentary on the Cook County property tax appeal landscape. The wrong answer is paralysis: missing the appeal window and then absorbing whatever the 2027 bill says.
How do I appeal my 2026 Cook County reassessment
File a free appeal with the Cook County Assessor during your township's open window, then, if needed, appeal again to the Cook County Board of Review later in the year. The Assessor's window generally opens when your township's notices mail and runs for several weeks; for example, the early 2026 townships such as River Forest and Riverside had filing deadlines in early June 2026 per the assessment calendar. You do not need a lawyer for a residential appeal, though many owners use one or an appeal service on contingency.
Strong residential appeals usually rest on one of three arguments: comparable homes in your neighborhood are assessed lower, a recent appraisal or purchase price shows a lower market value, or the Assessor's description of your property is simply wrong. Gather photos, comparable property index numbers, and any documentation of condition problems. Check your exemptions at the same time, because a missing homeowner or senior exemption costs real money regardless of the assessment. Our Cook County Assessor's office guide explains the mechanics, the evidence types, and the Board of Review stage in detail.
Is it a good time to sell in the south suburbs in 2026
For many owners, yes, and the reassessment is one reason among several. Selling in 2026 means closing before the reassessed values reach the 2027 second installment bills, which removes the biggest unknown from the transaction for both sides. Inventory across much of south suburban Cook County remains thin, demand for affordable homes within reach of Chicago is steady, and a house that would struggle to absorb a higher tax bill can still be a strong sale today. None of that is a guarantee, and local conditions vary block by block, which is why we look at the specific property before talking numbers.
An as-is cash sale fits a specific subset of these owners: those with delinquent taxes accruing interest, homes needing roofs, furnaces, or foundation work that retail buyers will not finance, inherited houses tangled in family logistics, or landlords done with a tenant property. In those files, the cost of holding through another tax cycle, repairs, carrying costs, interest, and risk, often exceeds the discount of a direct sale. We buy throughout Bloom, Thornton, Bremen, Rich, Calumet, Worth, Proviso, and the other 2026 townships, we price the tax picture into the offer honestly, and we close on the seller's schedule. If the notice has you weighing both paths, send the address and the notice, and we will give you a number to compare against the appeal-and-hold route.
Frequently Asked Questions
Which Cook County townships are reassessed in 2026?
The 2026 triennial cycle covers the south and west suburban townships of Cook County: Berwyn, Bloom, Bremen, Calumet, Cicero, Lemont, Lyons, Oak Park, Orland, Palos, Proviso, Rich, River Forest, Riverside, Stickney, Thornton, and Worth. Notices are mailed township by township, starting in late April 2026 and continuing through the summer.
How much will my property taxes go up after reassessment?
A reassessment does not automatically raise your taxes. Your bill depends on how your assessment changed relative to other properties in your area, the levies set by local taxing districts, your exemptions, and the results of appeals. If your assessment rose less than the local average, your bill can even fall. The prior south suburban cycle in 2023 produced steep increases for many owners, which is why reviewing the notice matters.
Should I appeal or sell after my reassessment?
Appeal first if you plan to keep the home, because appeals are free, can be filed with both the Assessor and the Board of Review, and a successful reduction generally lasts the rest of the three-year cycle. Selling makes more sense when the bill is already unaffordable, the home needs repairs you cannot fund, taxes are delinquent, or you were planning to move anyway and want out before higher bills land in 2027.
How do I appeal my 2026 Cook County reassessment?
File a free appeal with the Cook County Assessor during your township's open window, which generally runs for several weeks after notices are mailed, using comparable properties, an appraisal, or evidence of errors in your property's description. If that result disappoints, you can appeal again to the Cook County Board of Review later in the year. Exact deadlines by township are posted on the Assessor's assessment calendar.
When will the 2026 reassessment hit my tax bill?
Generally on the second installment bill issued in 2027, because Cook County bills a year in arrears, and the new values then shape bills through 2028 and 2029 until the next reassessment. The Cook County Treasurer sets exact billing dates each year, so check the current schedule rather than assuming a date.
Is it a good time to sell in the south suburbs in 2026?
It can be, depending on the property and the owner's situation. Inventory remains tight in many south suburban Cook County markets, and selling before reassessment-driven bills arrive in 2027 lets an owner avoid the uncertainty entirely. Owners with delinquent taxes, needed repairs, or fixed incomes facing rising carrying costs often benefit most from selling as-is rather than waiting out the cycle.
Decide with real numbers, not a scary notice
Send the address, the reassessment notice, your current tax bill, and your exemption status. We will review the property facts and tell you what a direct as-is sale would look like next to the appeal-and-hold path.