Glossary Of Commonly Used Terms


To place a value on property for tax purposes.

Assessment Level

The percentage of value at which property is assessed.

Assessment Review

The review of an assessment placed on a property. The first place to appeal an assessment is at the Assessor’s Office; the second level of appeal is the Board of Review (BOR); the third avenue for appeal is the Property Tax Appeal Board; the fourth is to file an objection in Circuit Court (only if filed at BOR).

Assessed Value

The fair market value multiplied by the assessment level for a class of property.


The process of dividing property into various classifications for purposes of taxing them at varying levels of assessment.

Equalized Assessed Valuation (EAV)

The assessed valuation multiplied by the equalization factor.

Equalization Factor

A factor determined by the Illinois Department of Revenue each year to ensure an equal assessment among all 102 counties in the state. State statute requires that the aggregate value of assessments within each county must be equalized at 33 1/3% of the estimated fair market value of real property in the county. This factor is also known as the "multiplier."


Release from liability for a portion of property taxes.


The calculation of the tax rate by the County Clerk based on the local municipality’s tax levy.

Fair Market Value (FMV)

The value the Cook County Assessor places on each parcel of real estate.

Market Value

The value placed on a property for assessment purposes.

Property Tax

The local tax on the value of real property, land, buildings and homes.


A mandatory payment to the government in order to fund government services.

Tax Base

The total body of tax revenues.

Taxing Body

Units of governments that collect taxes to fund government services (the City of Chicago, Chicago Board of Education, Chicago Park District, County of Cook, and local school districts.)

Tax Incentives

Incentives include exemptions, deferrals, abatements or tax credits. Incentives were established to stimulate a specific type of new growth for certain types of properties (i.e. affordable housing) or growth in areas of economic need.

Tax Levy

The amount in real estate taxes requested by each taxing body.

Tax Rate

The tax levy divided by the total equalized assessed valuation. This figure is compiled by the Cook County Clerk and applied to the equalized assessed valuation to determine the amount paid in property taxes.