I have been doing property tax work in Lake County long enough to notice a pattern that keeps repeating itself. An owner calls, frustrated, holding an assessment notice that treats his building like it is thriving. Meanwhile, half the lobby directory is blank, and the parking lot has room to spare.
The numbers back up what owners see with their own eyes...Suburban Chicago office vacancies
closed 2025 at a record 32.9 percent, according to JLL data reported by Crain's, up from 32 percent the year before. That was the twentieth straight quarter of record highs going back to early 2021. By the first quarter of 2026, CBRE put direct vacancy at 28.7 percent and climbing. There has been a little relief since then. Crain's reported suburban vacancy edged down slightly in the second quarter of 2026, the first quarterly dip since before the pandemic. But even after that dip, we are still talking about roughly a third of suburban office space sitting empty.
That is not a small blip. That is a structural shift in how much office space this region actually needs, and it has been going on for nearly 7 years.
So why does this matter for your tax bill? Because a county assessor is supposed to be estimating what your property would actually sell for, and a building's value is tied directly to what it produces. An office building that is sitting mostly vacant is not producing rent. It may also be have deferred maintenance or outdated systems such that a prospective tenant simply is not interested in it anymore. All of that pulls real market value down.
The problem is that assessments do not always move with the market in real time. A property can carry an assessed value based on outdated assumptions about occupancy and income long after the building itself has changed. When that happens, the owner is paying taxes on a version of the building that no longer exists.
If your building is sitting partially or fully vacant, it is worth asking whether your assessment has caught up to that reality yet. In a market where a third of suburban office space in Chicagoland sits empty, there is a good chance it has not.
Ron Kingsley
Attorney at Law
Master of Laws in Taxation
Lake County Appeal
About the author
Ron Kingsley leads Lake County Appeal, one of the most successful property tax appeal firms in Lake County. He earned his Juris Doctorate from Loyola University of Chicago in the early 1980s, his Master of Laws in Taxation from DePaul University in the late 1980s and has run Lake County Appeal since 2014, with a focus on commercial property tax appeals.