Historical permit data submitted by municipalities to the Cook County Assessor's Office.

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.

Additional notes: Almost all of the data in this dataset, such as address, estimated date of completion, work description, and permit amount, is data submitted by municipalities to the CCAO. The CCAO verifies or corrects the PIN number, determines whether the work is assessable, updates the status of CCAO workflows (e.g., open or closed), and sets the recheck year.

In addition to permits that are already closed, this dataset includes permits that are currently open or pending. These permits are not final and are subject to change. Data will be updated monthly. Rows are unique by the combination of "pin", "permit_number", and "date_issued". Job codes and improvement codes are not correct in all cases. Consider "work_description" to be the canonical description of the work that the permit describes. In many past cases permits have been submitted in irreconcilably different formats by different municipalities, or not at all. As such, this dataset does not represent the complete universe of permits in all municipalities, but rather represents the universe of permits that the CCAO knows about. Each row represents a parcel and a permit that is associated with that parcel. Permits may be associated with multiple parcels, and parcels may be associated with multiple permits. "date_issued" is more reliable than "date_submitted". Prefer "date_issued" when making temporal comparisons between parcels. Data for the current tax year may not yet be complete or final.

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.