Cook County Property Tax Appeal Assessments

Parcel-level assessed values pre and post-appeal for all Cook County properties from 1999 onward. The Cook County Assessor's Office uses this data for reporting, performance evaluation, and research. Data includes currently open appeal cases and is updated monthly.

Use Cases

• Analyze the impact of appeals on assessed values by comparing `mailed_tot` and `certified_tot` columns.
• Identify common appeal outcomes by examining the `change` and `status` fields across different `township_code` and `class` values.
• Track appeal agent activity over `tax_year` using the `agent_name` and `agent_code` columns.
• Investigate reasons for appeals by analyzing the `reason_desc1`, `reason_desc2`, and `reason_desc3` columns.
• Study appeal hearing patterns by filtering on `hearing_type` and `appeal_type`.

Strengths

• Includes data from 1999 to present, providing over two decades of historical coverage.
• Contains parcel-level detail with columns for building, land, and total assessed values at mailed and certified stages.
• Data is updated monthly, offering regular updates on appeal statuses.

Limitations

• Appeal data is sparse prior to 2021 due to a system transition, with incomplete reason, agent, and type fields for those years.
• Includes currently open appeal cases where data is not final and subject to change.
• Does not contain final assessed values after Board of Review appeals, requiring joins with another dataset.

Provenance

Source

Cook County Assessor's Office via datacatalog.cookcountyil.gov.

Collection Method

Administrative records from the property tax assessment and appeal process.

Time Range

1999 to present.

Freshness

Updated monthly.

Geography

Cook County, Illinois, USA.