Assessor - Assessed Values

Important notes: Assessed values are available in three stages: 1) mailed, these are the initial values estimated by the Assessor's Office and mailed to taxpayers. 2) certified, these are values after the Assessor's Office closes appeals. 3) Board of Review certified, these are values after the Board of Review closes appeals. The values in this data are assessed values, NOT market values. Assessed values must be adjusted by their level of assessment to arrive at market value.

Note that levels of assessment have changed throughout the time period covered by this data set. This data set will be updated roughly contemporaneously (semi-monthly) with the Assessor's website as values are mailed and certified. However, note that there may be small discrepancies between the Assessor's site and this data set, as each pulls from a slightly different system.

If you find a discrepancy, please email the Data Department using the contact link below. This dataset contains data for the current tax year, which may not yet be complete or final. Assessed values for any given year are subject to change until review and certification of values by the Cook County Board of Review , though there are a few rare circumstances where values may change for the current or past years after that.

Rowcount for a given year is final once the Assessor has certified the assessment roll all townships. Current property class codes, their levels of assessment, and descriptions can be found on the Assessor's website . Note that class codes details can change across time.

For more information on the sourcing of attached data and the preparation of this dataset, see the Assessor's Standard Operating Procedures for Open Data on GitHub. Read about the Assessor's 2025 Open Data Refresh.