ParcelProof

Blog · Basics · 2026-08-05 · 2 min read

Who actually set your value: township assessor, Supervisor of Assessments, or Board of Review

Three offices, three different jobs. Sending your argument to the wrong one wastes the only window you get.

Illinois property assessment involves several offices with similar-sounding names, and appeals get sent to the wrong one constantly. Here is who does what.

Outside Cook County

OfficeWhat it doesAppeal to it?
Township AssessorSets the initial value for parcels in that townshipInformally, before the roll publishes
Supervisor of AssessmentsCounty officer; equalises between townships, applies exemptions, publishes the rollSometimes, by county practice
Board of ReviewHears formal appeals; can raise, lower or confirmYes — the formal route
Property Tax Appeal BoardState body; hears appeals from the Board of ReviewYes, after the Board

Not every county has township assessors. In some, the Supervisor of Assessments does the work directly.

In Cook County

Cook is structured differently, and the difference matters because it gives you two bites.

  • The Cook County Assessor values every parcel in the county. There are no township assessors setting values.
  • You may appeal to the Assessor first, during your township's open period. This costs nothing and cannot raise your assessment.
  • You may then appeal to the Board of Review, a separate elected body, whether or not you appealed to the Assessor.
  • After the Board, the Property Tax Appeal Board or the Circuit Court.

These are genuinely separate bodies with separate records. In our analysis of the Assessor's published decisions — 1.79 million of them — roughly 23% resulted in a reduction. The Board of Review keeps its own record and its own rates; a refusal at one stage says nothing definitive about the next.

The practical sequence

  1. Read your notice and find the deadline. It is typically 30 days from publication of your township's roll and it is strict.
  2. Call the office that set the value — the township assessor outside Cook, the Assessor in Cook. A factual error in the record, like a wrong floor area, can sometimes be corrected here without a formal appeal at all.
  3. File formally with the Board of Review if that does not resolve it, or in Cook with the Assessor first and then the Board.
  4. Escalate to the Property Tax Appeal Board if you disagree with the Board of Review.

The one asymmetry worth knowing

At the Cook County Assessor stage, an appeal cannot increase your assessment. The Board of Review, by contrast, has the authority to raise as well as lower — in practice rarely exercised for residential property, but it is a real difference between the two stages and worth knowing before you decide how far to take a marginal case.

Who to talk to about what

  • The record is wrong — the office that set the value.
  • An exemption is missing — the Supervisor of Assessments outside Cook, the Assessor in Cook. This is not an appeal and does not use the appeal process.
  • The value is unfair — the Board of Review, formally, in writing, before the deadline.
  • The tax rate is too high — none of them. That is set by the levies of your school district, municipality and other taxing bodies, and is a question for those boards.
This is general information about how Illinois assessments and appeals work. It is not legal advice, not an appraisal, and not a prediction about your case. Deadlines and rules differ by county — check yours with your Board of Review.

Check your own assessment free →

More on Basics

← How to read your assessment notice · Quadrennial reassessment: the year your number actually gets rebuilt →