Land, building, and total assessed values for all Cook County parcels, from 1999 to present. The Assessor's Office uses these values for reporting, evaluating assessment performance over time, and research.

When working with Parcel Index Numbers (PINs) make sure to zero-pad them to 14 digits. Some datasets may lose leading zeros for PINs when downloaded.

This data is parcel-level. Each row contains the assessed values for a single PIN for a single year. 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 (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.

The Parcel 2016 feature contains tax parcel polygons for the 2016 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2016 through 12/31/2016. Each parcel is uniquely identified with a Property Index Number (PIN).

Tax code rates for Tax Years 2006 through 2013. Data is updated yearly. For more information on Tax codes visit the Cook County Clerk's website at: http://www.cookcountyclerk.com/tsd/Pages/default.aspx

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.

The intake data presented in this data reflects the cases brought in for review. Each row represents a potential defendant in a case.
Please use this link for more instructions and data glossary:
https://www.cookcountystatesattorney.org/resources/how-read-data

The Parcel 2012 feature contains tax parcel polygons for the 2012 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2012 through 12/31/2012. Each parcel is uniquely identified with a Property Index Number (PIN).

The Independent Inspector General submits Quarterly Reports to the MWRD Board of Commissioners and Executive Director. The Quarterly Report is released the 15th day of January, April, July, and October of each year. Quarterly Reports chronicle the number and type of investigations initiated, concluded or pending since the date of the last report and whether any recommendations for remedial action were made and whether or not the recommendations were followed by the MWRD.