What the Equalizer Is Supposed to Do

Illinois law says property is supposed to be assessed at one-third of market value, 33.33%. That’s the statewide target. In most counties, it’s simple. But Cook County runs on a classification system. Residential starts at 10% of market value. Commercial starts at 25%.

To bring the county average back in line with that 33.33% target, the Illinois Department of Revenue applies a single multiplier each year called the equalizer.

Why a Single Multiplier Creates a Problem


That one-size-fits-all multiplier wasn’t designed for a place like Cook County. When you apply the same equalizer to both residential and commercial, you end up with two very different outcomes.

  • Residential gets pulled upward from 10% toward 33.33%
  • Commercial gets shoved way past 33.33% because it’s already starting at 25%

Take 2023 for example. The multiplier was 3.0163. Do the math:

  • Residential effective level = 10% × 3.0163 = 30.16%
  • Commercial effective level = 25% × 3.0163 = 75.41%

That’s the problem in plain sight. If a commercial owner does nothing, they’re basically being taxed on 75% of their property’s market value. The law says 33.33%, but the system pushes them into double that.

Why the Appeal Industry Exists

This is the real origin of the appeal industry in Cook County. It didn’t spring up because lawyers wanted another income stream. It sprang up because commercial owners had no choice. If they don’t appeal, they’re paying taxes on values that no statute ever intended.

Over time, boutique firms and consultants grew to fill that gap. Sure, some people in the system benefit from keeping it messy. But the industry itself is a response to the imbalance the equalizer creates, not the cause of it.

The Constitutional Question

On paper, it looks unconstitutional. How can one class of property be taxed at 75% while another sits closer to 30%? But Illinois courts have consistently said it’s fine. Their argument: as long as all commercial property is treated the same within its class, the system is “uniform.”

That’s the legal interpretation that keeps the one-size-fits-all multiplier in place. In practice, though, it means commercial property owners are forced to fight their way back to fairness every single year.

The Bottom Line

The equalizer is supposed to level things out. Instead, it’s the reason commercial owners are constantly in appeals. Residential gets nudged closer to the target. Commercial gets crushed. Until the system changes, appeals aren’t about working the system, they’re about surviving it.

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