Assessor - Assessed Values
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 semi-monthly. Note that the refresh may or may not correspond to the Assessor's schedule of mailing and certifying assessments.
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 (pdf) and in this class code dictionary (csv). Note that class code 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.
See additional datasets in the Assessor's Open Data Catalog.
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Complete Metadata
| @type | dcat:Dataset |
|---|---|
| accessLevel | public |
| contactPoint |
{ "fn": "Cook County Assessor's Office Data Department", "@type": "vcard:Contact", "hasEmail": "mailto:no-reply@datacatalog.cookcountyil.gov" } |
| description | 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:<ul><li>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.</li> <li>The values in this data are assessed values, NOT market values. Assessed values must be adjusted by their <a href="https://prodassets.cookcountyassessoril.gov/s3fs-public/form_documents/classcode.pdf">level of assessment</a> to arrive at market value. Note that levels of assessment have changed throughout the time period covered by this data set.</li> <li>This data set will be updated semi-monthly. Note that the refresh may or may not correspond to the Assessor's <a href="https://www.cookcountyassessoril.gov/assessment-calendar-and-deadlines">schedule</a> of mailing and certifying assessments.</li> <li>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.</li> <li>Rowcount for a given year is final once the Assessor <a href="https://www.cookcountyassessoril.gov/assessment-calendar-and-deadlines">has certified the assessment roll</a> all townships.</li> <li>Current property class codes, their levels of assessment, and descriptions can be found <a href="https://prodassets.cookcountyassessoril.gov/s3fs-public/form_documents/classcode.pdf">on the Assessor's website (pdf)</a> and <a href="https://github.com/ccao-data/data-architecture/blob/master/dbt/seeds/ccao/ccao.class_dict.csv">in this class code dictionary (csv)</a>. Note that class code details can change across time.</li></ul> For more information on the sourcing of attached data and the preparation of this dataset, see the <a href="https://github.com/ccao-data/wiki/blob/master/SOPs/Open-Data.md">Assessor's Standard Operating Procedures for Open Data</a> on GitHub. See additional datasets in the <a href="https://datacatalog.cookcountyil.gov/stories/s/gzdr-q7c4">Assessor's Open Data Catalog.</a> |
| distribution |
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| identifier | https://datacatalog.cookcountyil.gov/api/views/uzyt-m557 |
| issued | 2025-09-11 |
| keyword |
[ "cook county assessor", "property tax" ] |
| landingPage | https://datacatalog.cookcountyil.gov/d/uzyt-m557 |
| modified | 2026-10-20 |
| publisher |
{ "name": "datacatalog.cookcountyil.gov", "@type": "org:Organization" } |
| theme |
[ "Property & Taxation" ] |
| title | Assessor - Assessed Values |
