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Two properties are comparable to each other if they have similar characteristics. Properties that are comparable to each other should have similar assessed values.
The tool recommended by our office to find comparable properties is Cook Viewer's Interactive Map. This is a free tool created by Cook County GIS. It allows you to see exactly which properties are considered comparable to yours in Cook County's property database.
You can use it to find your property, then click on your property, and then click on "Compare this Property."
This online mapping tool will automatically apply filters based on neighborhood, class, square footage, and age to find properties that are comparable to yours.
The comparable properties will be shown on an interactive map so you can see that property's location relative to the subject property, its characteristics, and assessment information.
To find properties that are comparable to yours:
This online mapping tool is a useful way to compare properties and their assessed values.
Sometimes the Neighborhood Search is used to find comparable properties. It is important to remember that even if two homes have the same township, neighborhood, and class, they may not necessarily be comparable. They must also be similar in characteristics like age and square footage.  Because Cook Viewer will automatically apply these filters for you, we recommend it.
You can read the Cook County Assessor's guide on what it means for two homes to be (or not be) comparable: What are comparable properties?
How to attach comparable properties with your online appeal:
If you are filing an appeal online because you believe your home has not been assessed uniformly relative to other comparable properties, CCAO analysts will analyze comparable properties in the CCAO database to make a determination about the uniformity of your property's assessment. You also have the option of attaching comparablePINs from your research to send to the analyst, but it is not required: CCAO analysts will conduct an analysis of comparable properties for you.
If you are filing your appeal online and you are attaching comparable properties for an appeal reason of "Lack of Uniformity," you may upload information about up to six (6) comparable PINs and must use specific file names.
To attach comparable properties with your appeal requires some specific steps. You have two options. The list of steps is broadly previewed below, but you can also read step-by-step instructions with images.
Then, enter your property's address or PIN.
Click on "Compare properties." Find properties that are comparable to yours.
There are two ways to attach up to 6 comparable PINs with your appeal. Either:
Print and save each PIN's information as a PDF. For example, if the first comparable PIN is 01-23-456-789-1000, the file would be saved with the filename Comparable PIN 01-23-456-789-1000.pdf.
Export a list of up to 6 comparable PINs into one Excel (.xlsx) file, named Comparable PINs for xx-xx-xxx-xxx-xxxx.xlsx (with each x representing the PIN digit in your property.)
In the Attachments tab, attach your comparable PIN file(s) in the portion of the online appeal that asks for comparable PINs.
For more specifics, please read our extensive step-by-step guide on how to use Cook Viewer to find PINs that are comparable to your home, export the list of comparable PINs, and attach up to 6 comparable PINs with your online appeal here.