The Cook County assessment system for income-producing property runs on the logic of the income cap strata.Subclass dictates vacancy percentages and cap rates. Tax district codes dictate expense percentages.

By applying the tax estimation formulas of both the Assessor and the Board of Review, we can calculate taxes, measure the gap between them, and back into the operating expense percentage applied per property. This is where hidden NNN leases begin to surface.

Macro-analysis, powered by data science, is often a process of navigating ambiguity. The information is incomplete, the leases are not labeled, and the operating expense percentages often come pre-filled from opaque sources. To make sense of it, you work through messy data until the patterns reveal themselves.

What the Analysis Reveals

  • Assessor vs. Board of Review
    Two different ways of handling taxes that often create measurable valuation gaps.
  • Subclass and NNN Leases
    Vacancy percentages and cap rates tied to subclass, with hidden triple net leases lurking inside the data.
  • Strata Levers
    The controlling variables that determine how properties are slotted and valued.
  • Investment Class Cheat Sheet
    A quick reference guide for which arguments are effective in appeals.
  • Tax Rate Heat Map
    A geographic view of how tax rates shift across districts.
  • Cap Rate Heat Map
    A visualization of risk and value perceptions at the county level.

Why It Matters

When you put these pieces together, the picture becomes clearer. The system is not random. It runs on a framework of strata, subclasses, and district codes. By navigating ambiguity with structured analysis, you can reveal where the levers are and how to use them.

Explore the Workbook

The full Excel workbook is available to download below. It contains all the tabs, calculations, and heat maps referenced in the analysis, organized as chapters you can follow directly (as shown in the October 2nd edition:

  1. Assessor vs. Board of Review
  2. Subclass and Triple Net Leases
  3. NNN Lease Vs. non-NNN Lease
  4. Strata Levers
  5. Investment Class Lever Cheat Sheet
  6. Tax Rate Heat Map
  7. Cap Rate Heat Map

Download:

Spreadsheet from Tax Analysis Show – October 2nd 2025

###