Your Neighbor's Assessment Jumped 25 Percent. Their Tax Bill Might Go Down. Yours Might Not.

Every property owner in Oak Park opened the same envelope this spring. The Cook County Assessor's Office estimated that home values across the village rose by an average of 25 percent since the last reassessment in 2023, with the notices landing in mailboxes on May 6. That single number has been repeated in every conversation about Oak Park real estate since, usually followed by some version of "so my taxes are going up 25 percent too."

They're probably not. And the reason why is the part almost nobody explains, which matters right now because the window to do something about it closes tomorrow, September 1.

The 25 percent number measures something different than your tax bill

A reassessment updates the county's estimate of what your home is worth. It does not, by itself, set your tax bill. What actually determines your bill is your home's share of Oak Park's total tax burden, which the Oak Park Township Assessor's office has put at roughly $264 million a year. That burden is set by local taxing bodies, mainly the schools, the village, and the park district, and it typically rises a little each year under state levy caps. A reassessment doesn't grow or shrink that pool of money. It just redraws how the pool gets divided among every property in the township.

That distinction produced a real, documented split last cycle. After Oak Park's 2023 reassessment, roughly a third of homeowners saw their tax bills go down even as the village's overall assessed value climbed, while about 40 percent saw double-digit increases. Same reassessment, same village, wildly different outcomes depending on how each home's value moved relative to everyone else's.

The mechanics work like this: Cook County sets residential property at 10 percent of its estimated market value to get an assessed value, then multiplies that by a state equalizer to arrive at the Equalized Assessed Value, which is the number actually taxed. A $500,000 home carries a $50,000 assessed value, and with a hypothetical 3.0 equalizer that becomes a $150,000 taxable base. If your home's estimated value rose exactly in line with the village average, your share of the tax burden barely moves and your bill likely tracks the modest, capped annual increase that would have happened anyway. If your home's estimated value rose faster than the village average, more of the $264 million lands on your bill. If it rose slower, less does.

This won't hit tax bills until they're issued in the summer of 2027, but the assessed values driving those bills were locked in based on your property's status as of January 1, 2026, which is exactly why the current appeal window matters more than the reassessment notice itself.

Single-family, condo, and townhome owners are not experiencing the same reassessment

The village-wide 25 percent figure hides a spread that's worth understanding if you own, or are shopping for, a specific type of Oak Park property. According to figures the Oak Park Township Assessor shared with the Wednesday Journal, single-family homes rose about 24 percent on the median, condos rose about 25 percent, apartment buildings rose 28 percent, commercial property rose 21 percent, and townhomes rose only 11 percent.

That last number stands out. Townhome owners are absorbing less than half the assessed increase that single-family and condo owners are seeing. Since the levy pool is fixed, a smaller relative increase in a property's assessed value generally means a smaller relative increase in its share of the tax burden going forward, all else equal. For anyone comparing carrying costs between a condo and a townhome purchase this fall, that gap is a real input, not a footnote. It won't show up on a listing sheet, and it won't show up in a Zestimate. It shows up in the township's own reassessment breakdown, and it's the kind of detail that only surfaces when you're paying attention to how a specific market moved, not just what it's worth today.

The window that's still open, and the one piece of leverage buyers just got

Here is the part with an actual deadline attached. Property owners who were unhappy with their May reassessment, or who never filed an appeal with the County Assessor at all, have a second chance through the Cook County Board of Review. Oak Park Township's window opened August 3 and closes September 1, tomorrow, according to the Oak Park Township Assessor's office and confirmed in the Wednesday Journal's August 4 coverage. There is no fee to file, and Oak Park Township's assessor staff will help residents prepare an appeal if you call ahead of the deadline.

The strongest and most straightforward ground for an appeal is one that a lot of recent buyers don't realize applies to them: if you closed on your Oak Park home in the past year or so, and the price you actually paid is lower than the Fair Market Value estimate on your reassessment notice, that purchase price is direct evidence the county's estimate is too high. The same goes for a recent independent appraisal. Other accepted grounds include:

• Comparable nearby properties assessed at a lower value for similar square footage and condition
• An incorrect property record, such as wrong square footage or a listed feature that doesn't exist
• A recent arm's-length purchase price below the estimated market value on the notice

If you bought in Oak Park within the last year and your closing statement shows a number below what the county now says your home is worth, that document alone is worth a phone call to the Township Assessor's office before the window shuts.

What this means if you're listing or closing this fall

If you're preparing to list an Oak Park home this fall, expect buyers and their agents to ask about the reassessment, and have a real answer ready rather than a shrug. Knowing whether your property's assessed increase tracked the village median, whether you appealed, and where that appeal landed lets you have a grounded conversation about future carrying costs instead of guessing alongside the buyer. Sellers of condos and single-family homes, where the increase ran closer to a quarter, are more likely to field this question than sellers of townhomes, where the smaller 11 percent bump makes the conversation shorter.

If you're closing on a purchase in the next few weeks, ask directly whether the seller filed an appeal with the County Assessor back in June, what the outcome was, and whether they intend to file with the Board of Review before tomorrow's deadline. If they haven't and your purchase price came in under the notice value, you may want to file yourself once you're the owner of record, since the right to appeal typically follows ownership at the time of filing.

A few questions we hear often

Does a 25 percent higher assessment mean my property is now worth 25 percent more? Not necessarily. The reassessment notice reflects the county's estimate of market value based on sales trends in your area over the past few years, not an appraisal of your specific home. Village-wide, the median Oak Park sale price moved from $513,000 at the 2023 reassessment to $595,000 at this year's, which is the underlying trend driving the county's estimate, but any individual property can move above or below that trend.

If I missed the June 18 Assessor deadline, is the appeal process over? No. The Board of Review is the second level of appeal, and it's open for Oak Park Township now through September 1. This is a separate process from the Assessor's office, and outcomes can differ between the two.

Will this affect my 2026 tax bill? No. These changes affect tax bills starting with the second installment issued in the summer of 2027, based on your property's status as of January 1, 2026.

Does a lower assessment automatically mean lower taxes? Only relative to what your bill would have otherwise been. Because the total tax burden is fixed and divided by share, a successful appeal lowers your portion of that burden, which typically translates to real savings, but it won't erase the underlying levy increase that happens most years regardless of reassessment.

Property tax mechanics rarely make for light reading, but they shape what a home actually costs to own long after closing day. If you're weighing a sale this fall, sorting through a reassessment notice, or trying to understand what a specific Oak Park property will really cost to carry, ZK Group can walk through the numbers with you and help you decide whether tomorrow's deadline is one worth acting on. Schedule a consultation and let's look at your specific situation before the window closes.