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CCFB News» February 2020

Get to know your local official: County Assessor

Primary Duties

The Chief County Assessment Officer (CCAO), or supervisor of assessments, is responsible for assessing the value of all real property within their jurisdiction for the purpose of real estate taxation. The assessment process plays an important role in local government. Equitable assessments assure property owners are paying their fair share of the costs of operating schools, providing police and fire protection, road construction and maintenance, and other

basic public services.


The assessor is concerned with value, not taxes. The assessor does not collect taxes, calculate taxes or determine the tax rate. Taxing jurisdictions such as schools, cities, and townships, adopt budgets which determine the tax levy. The actual dollar amount of your tax bill is determined by how much money these local agencies need to operate. Every dollar of property tax remains in the local area to fund local government.


Property is assessed as of January 1 each year. The CCAO, in conjunction with township assessors, where applicable, determines a full or partial value of new construction or improvements. In Illinois, a legal assessment is 33.3 % of value. To estimate value, the assessor generally uses three approaches.

  1. Find properties that have sold recently and are comparable to the property being assessed
  2. The “cost approach” is an estimate of how much money it would take to replace the property with one similar to it
  3. Known as the “income approach” this is used to assess property such as an apartment or office building which produce income. State law requires that all real property be reassessed every four years


After the assessor places a property value on each parcel of land in the county, the board of review hears complaints and determines those property values. The Illinois Department of Revenue analyzes the assessments in every county throughout the state and determines the State Equalization Factor. This multiplier is then applied to those counties’ assessments which fall below the statutory 33.3 level of property value. The county clerk then reviews the taxing jurisdiction budgets and determines the tax rates that should be applied to the assessments based on the estimated expenditures for each unit of local government. The county treasurer calculates the tax bills, mails them out, and collects the tax dollars.


Other Responsibilities

The county assessor is the clerk of the board of review and is present at all hearings. The board of review hears complaints from taxpayers concerning real estate assessments and renders decisions regarding values of property. The county assessor also prepares and maintains up-to-date tax maps, lists of property owners’ names and addresses, and property record cards.



To be eligible for the office of supervisor of assessments, a person must possess one of the following:

  1. Certified Illinois Assessing Official certificate from the Illinois Property Assessment Institute
  2. Certified Assessment Evaluator certificate from International Association of Assessing Officers
  3. Member of Appraisal Institute, Residential Member, and Senior Real Estate Analyst


In addition, a person must have passed an examination conducted by the Department of Revenue.



Supervisor of assessments are elected or appointed by the county board and serve a four-year term.

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