Any La Grange listing you look at this month shows an annual property tax figure. That number comes from tax-year-2025 bills. Those bills were based on values set before Cook County reassessed Lyons Township in 2026, and the second installment was due October 1, 2026. According to the Cook County Assessor's Lyons Township residential page, the new values on this summer's reassessment notices "will be reflected on tax bills in 2027." For a buyer comparing La Grange with nearby towns, the tax line on a listing is a reading from the previous cycle.
The headline figure for the new cycle is large. La Grange Daily reported a nonofficial CookCountyTaxCheck.com analysis. It found the typical Lyons Township house's first-pass 2026 assessed value was about 24.4% higher than its final 2025 value, based on a median of 30,233 houses. That percentage tells you little about next year's bill. The last time Lyons Township was reassessed, the change that moved homeowners' bills came from the appeal stage that followed. The 2026 cycle is the first to run under a rate method the Assessor and Board of Review designed together.
Where the 2026 cycle stands on publish day
The Assessor mailed Lyons Township reassessment notices on July 23, 2026, and the Assessor appeal deadline was September 3. The Cook County Board of Review then opened Lyons, as part of its Group 3, on October 8 and closed new filings on November 6. As La Grange Daily noted, the Board's decision "sets the final county assessed value for the year."
| Tax year | Assessed values it uses | When the bill lands |
|---|---|---|
| 2025 | Year three of the 2023 Lyons cycle | Second installment due Oct. 1, 2026 |
| 2026 | New 2026 reassessment, after appeals | Second installment issued in 2027 |
The Assessor's township-wide numbers show where values landed. For 2026, the median estimated market value of a Lyons Township single-family home is $418,000. The 2025 median sale price for single-family homes was $462,000. For condos, the figures are $218,000 and $225,000. These are township-wide medians. Lyons covers La Grange, Western Springs and other villages, so they are not La Grange figures.
Why a higher value doesn't raise the bill by the same percentage
In Cook County, the tax rate is calculated last. Local governments set their levies. The Assessor sets assessed values and exemptions. The County Clerk then sets a rate so that assessed value multiplied by the rate produces the levy. The Treasurer bills and collects.
Because the levy comes first, a bigger total assessed value can mean a lower tax rate, as the Cook County Treasurer's property tax primer explains. Illinois' tax cap law, PTELL, generally limits annual levy growth for covered governments to the lower of inflation or 5%. The Civic Federation notes that exceptions mean the cap does not guarantee bills stay within that growth rate.
So a homeowner's bill depends on their share of the levy. If every property in a taxing district rose 24% and the levy held steady, the rate would fall and bills would barely move. Bills change when one group of properties rises faster than another and the levy shifts toward the faster-rising group. The Treasurer has also cautioned that a lower rate applied to a higher assessment can still produce a higher bill.
What moved the share last time
The 2023 Lyons reassessment shows how this works. The Assessor reported that Lyons Township's residential assessed value rose 32% before appeals, from $1,161.71 million in tax year 2022 to $1,530.02 million in tax year 2023.
The Treasurer's analysis of tax-year-2023 bills tracked what happened after that. For the south and southwest suburbs, a region that includes Lyons, the Assessor's values alone would have shifted about one half of 1% of the tax burden from homeowners onto commercial properties. Then the Board of Review cut the total assessed value of commercial and industrial properties that appealed by more than 21%. Residential properties that appealed were reduced by only about 4.4%. After the Board finished, about 4% of the burden had shifted from commercial properties onto homes.
| South/southwest suburbs, tax year 2023 | Direction of burden shift |
|---|---|
| Assessor's values, before Board of Review | About 0.5% from homes to commercial |
| After Board of Review adjustments | About 4% from commercial to homes |
Across the region, the dollar figures were large. Residential taxes rose $396.8 million, or 15.9%, while commercial taxes fell $121.6 million, or 7.8%. The south and southwest suburban median residential bill for tax year 2023 rose 19.9% to $6,117. The Treasurer called it the largest increase for a reassessed area in at least 29 years. The Treasurer gave three causes. One was the Board's commercial reductions. The other two were higher home prices and the end of a COVID-era cut of about 10% that the Assessor had applied to residential values in 2020.
In the later years of that cycle, growth was much slower. For tax year 2024, the regional median residential bill rose 2.2% to $6,258. For tax year 2025, the bills mailed this year, residential taxes in the south and southwest suburbs rose 3.8% and business taxes rose 4.3%, according to the Treasurer's August 2026 analysis. In this part of Cook County, the reassessment year is when the share moves.
The 2026 cycle runs under a different method
On May 26, 2026, the Cook County Property Tax Reform Group, led by Board President Toni Preckwinkle, announced a unified tax-rate methodology that the Assessor and the Board of Review will both use for tax year 2026. The change followed an independent audit of the County's commercial valuation methods. The audit found differences between the two offices and recommended updates to both offices' tax-rate and capitalization-rate practices.
The new framework applies first to the 2026 reassessment of the south and west suburbs. The County said this region has a "higher fluctuation of tax rates than other triads." The Assessor will estimate 2026 tax rates from the rate-change patterns of the 2023 reassessment, and the Board of Review will use the same method when it decides appeals this year. Separately, the Assessor's 2026 commercial policy no longer deducts property taxes as an operating expense. It adds a tax load to the capitalization rate instead.
Commercial valuation is where the 2023 shift came from, and it is the part of the process this reform changes. For an example in La Grange, the Assessor's initial 2026 commercial worksheet values a shopping-center property at 1 N. La Grange Road at $11,491,000. The Assessor notes that these worksheets record the initial mailed valuations and do not include changes from appeals. Once the Board of Review finishes its Lyons decisions, the final split between homes and commercial property will decide how the levy is shared on the 2027 bills.
What this changes in a La Grange comparison
A La Grange listing priced this winter shows a tax figure from the last year of the old cycle. A home in a town that was not reassessed this year shows a figure from mid-cycle. Neither number tells you next year's bill, but the La Grange figure is the one about to be reset. Two La Grange homes with similar tax lines today could get different 2027 bills. Their 2026 values may have moved at different rates, and the final commercial-to-residential split is still pending.
Owners who plan to sell in 2027 face the same timing from the other side. A buyer touring in spring will still see the tax-year-2025 figure, while the bill that reflects the reassessment arrives later. The timing of last cycle's bills also differed from the usual schedule. WTTW reported in June that the tax-year-2025 second installment would be about two months late.
Owners had local help with appeals this year. The Desplaines Valley News reported that Lyons Township Assessor Pat Hynes held a resident help session at Summit Park on August 13. It also announced a stop at La Grange Village Hall on August 17.
FAQ
Does Western Springs follow the same timeline? Yes, for the parts of Western Springs in Lyons Township. The Assessor says the township includes all or part of both La Grange and Western Springs. The Treasurer's tax-year-2023 analysis put Western Springs' average composite tax rate at 7.34%. It listed that rate among the lowest in the south suburbs.
Is the 24.4% increase official? No. La Grange Daily described it as a nonofficial estimate covering Lyons Township houses and said individual homes vary widely.
How have past Board of Review appeals gone for Lyons homeowners? The same CookCountyTaxCheck.com analysis looked at 7,837 appeals filed by owners themselves for tax years 2023 through 2025. About 54% received a lower assessed value, and the typical annual savings among those who did was about $769. Those figures are also nonofficial, and past results do not predict future outcomes.
This post is general information about how Cook County taxes are calculated, not tax, legal or financial advice. Please confirm the details for a specific property with a tax professional or attorney.
Pricing a La Grange home in 2027 means accounting for a tax bill buyers haven't seen yet. McCleary Group can show you how your home's 2026 value fits with recent sales and what buyers are likely to ask about. Request your complimentary home valuation.
