Equalizationis the adjustment of the median level of assessment
up or down so that the tax burden is "equalized" among taxing
State law requiresequalization in order to bring assessments to
the level required by state law, which is 33.33% of fair cash
Equalization is accomplished by the use of an Equalization
Factor, which is a factor applied to all non-farm assessments.
Equalization factors are applied at three levels:
Township level, as applied by the Supervisor of
Township level, as applied by the Board of Review.
County level, as applied by the Illinois Department of
WHAT EQUALIZATION FACTORS ARE NOT OPTIONAL:
To quote the state law: -35ILCS 200/9-210
With the ratio determined for each township or assessment
district, the supervisor of assessments shall then determine the
percentage to be added to or deducted from the aggregate
assessments in each township . . . in order to produce a ratio of
assessed value to fair cash value of 33 1/3%. That percentage shall
be issued as an equalization factor for each township or assessment
district within each county served by the chief county assessment
officer. The assessment officer shall then change the assessment of
each parcel of property by application of the equalization
Equalization is not a measure of change in property values
They reflect the difference between sale prices and the legal
level of assessment.
Equalization Factors are NOT arbitrary.
They must be calculated according to procedures prescribed and
taught by the Department of Revenue
The process involves the analysis of thousands of "arm's
An Equalization Factor is not a reflection of the accuracy of a
(Township Assessors are responsible to "revise and correct"
assessments in non-General Assessment years; equalization is a
post-correction change to bring those assessments in line with
other townships in the County).
A school district has a tax rate of $4.8411 per $100 of
valuation. The district is partially in Township A (33.33%
median level of assessment) and partially in Township B
Without equalization, the owner of a house in Township A pays
more property tax than the owner of a similar house in Township
$300,000 x 33.33%=$99,990 x 4.8411%=$4,841
$300,000 x 29.48%=$88,440 x 4.8411%=$4,281
Total Paid: $9,122
But afterequalization, the tax burden is uniform. Township B
has been equalized with a factor of 1.1306, bringing the median
level of assessments to 33.33%.
The change in aggregate EAV will lower the tax rate (to 4.5615
in this example). This results in the following tax
$99,990 x 4.5615%=$4,561
$88,440 x 1.1306=$99,990 x 4.5615%=$4,561
Total Paid: $9,122
STEPS IN CALCULATING TOWNSHIP EQUALIZATION FACTOR
Gather the Data
Real Estate Transfer Declarations from 2007, 2008, and 2009
(from form PTAX-203)
Assessment Data from 2006, 2007, and 2008 (from Board of
Review's Equalized Assessed Values)
2009 Assessment Books (from Board of Review's Certified
2010 Assessment Books (from Township Assessor)
Conduct a Three-Year Sales Ratio Study
Compare 2007 sales to 2006 Assessed Values
Compare 2008 sales to 2007 Assessed Values
Compare 2009 sales to 2008 Assessed Values
Calculate the median level (the point at which half of the data
is greater, and half is lesser) of assessment for each year
Calculate the Projected Equalization Factors
Adjust each year's median sales ratio to reflect the changes
made in the level of assessments (for each township)
For this example, the 2007 ratio was 30.91%; the 2008 ratio was
31.21%, and the 2009 ratio was 32.67%
The level of assessment (33.33%) is divided by the average of
the adjusted ratios to establish the 2010 Projected Township
2007 Adjustment is 30.91% x 1.0279 = 31.77%
2008 Adjustment is 31.21% x 1.0279 = 32.08%
2009 Adjustment is 32.67% x 1.0279 = 33.58%
Sum of the Adjusted Factors is 97.43%
33.33% ÷ 32.48% = the Township
Apply the Equalization Factors
This process is conducted for each of the 14 townships in
The assessments in each township are adjusted by that
township's equalization factor to provide an Equalized Assessed
Value (EAV) for each parcel.
The equalized assessments are then certified to the Board of
A property in the township used in this illustration with
an assessed valuation of $100,000 would have an
equalized assessed valuation of
($100,000 x 1.0262 = $102,620)
EQUALIZATION BY THE STATE
It is the job of the Illinois Department of Revenue to conduct
the same Sales Ratio Studies for each of Illinois' 101 counties and
equalize valuations across County lines within the State.
If individual townships are not successfully equalized to 33.33
(the statutory level), the State of Illinois will apply one uniform
State Equalization Factor to the entire county.
The Winnebago County State equalization factor has been 1.0000
(no further adjustment) for 20 consecutive years.
By comparison, Cook County's 2008 equalization factor was
2.9786, up from 2.8439 in 2007.