This data set contains characteristic data points used by the Cook County Assessor in the 2021 Chicago reassessment to produce initial estimates of the current market value of most Chicago homes (single-family homes, small multi-family homes, and condo units). You can use the "Filter" option to search for a property's PIN or address, and see what data the Assessor’s Office had about a home’s characteristics at the time of modeling*. To learn more about how the 2021 model used this data, read about our public Residential Automated Valuation Model here. Chicago properties not listed here are reassessed using different modeling procedures.

*Important Note: This dataset is, at the time of publication, an early snapshot of data. Data about a home might change later in the assessment process this year as Assessor’s Office staff and analysts review these properties. After this review, updated characteristics and market values are mailed to homeowners. If the data listed on the assessment notice is incorrect, an appeal can be filed to provide the correct characteristics.

Every assessed value in Cook County 2010 to 2020, and appeal indicators. Each PIN has three stages of assessments each year: CCAO Mailed, CCAO Certified, and Board of Review (BOR) Certified final values. This allows comparison in assessments across agencies.

This data displays total exempt EAV and total exemptions by tax code. Since residential exemptions reveal sensitive information about individual taxpayers and households, we have applied the p% statistical disclosure rule in suppressing fields.

Real estate sales data used by the Cook County Assessor to estimate Fair Cash Values for the purpose of property taxation. Deeds that include multiple PIN numbers are excluded from this data. This data is produced by joining sales data from the Illinois Department of Revenue against incomplete sales data from the Cook County Recorder of Deeds, parsing the resulting data to obtain data unique by deed number, and, in some cases, determining arms' length status of sales.

This data set includes property locations and attached spatial data for all Cook County parcels. Spatial matching was based on parcel centroids. Older properties may be missing latitude and longitude data because they are not contained in the most recent parcel shape layer. Brand new properties may be missing a mailing/property address because the postal service has not yet assigned the property an address. Data attached to each PIN is the most recent available. For example, Census tract data is drawn from the 2014-2018 5-year American Community Survey.

The code and sources used to construct this data can be located on GitLab. See data notes for link.

In response to the 2020 COVID-19 pandemic and its anticipated effects on the residential real estate market, the Cook County Assessor will adjust residential assessments. This data can be used to replicate residential COVID adjustments. Code can be located on GitLab. See data notes for link. NOTE that the 'adjusted values' in this data will not necessarily be consistent with each individual PIN's final assessment. To get the final assessment for an individual PIN, please visit www.cookcountyassessor.com.

Neighborhoods play an important role in residential property assessment. Single-family and residential multi-family property assessments are sensitive to neighborhood boundaries. Neighborhoods are nearly always used in statistical regression models to produce initial assessed values, and comparable properties are nearly always selected from within neighborhoods for the purposes of appeal. See data notes for additional information.

This data contains every residential Property Index Number (PIN) and corresponding Assessed Values from significant stages in the assessment process.

This data was replaced with the more comprehensive Cook County Assessor's Fair Cash Values.

A data set showing algorithmically determined sales comparables for single family properties in Lake Township

As of February 14, 2020 this dataset will be considered archived information and will no longer be updated.

First-pass property values as assessed by the Cook County Assessor in their Computer Assisted Mass Appraisal system used to assess residential properties. This dataset contains first pass values for 2019 and corresponds with residential PINs in the Cook County Assessor's Assessment Data. These are NOT final assessed values. For Disclaimers, see dataset narrative at https://datacatalog.cookcountyil.gov/stories/s/p2kt-hk36