This is an archive of bid tabulations before June 2016. For current bid tabulations see https://datacatalog.cookcountyil.gov/d/32au-zaqn. The bid tabulations provided herein are preliminary and are for informational purposes only. The purpose of providing this preliminary information is to improve process transparency. The information contained in the preliminary bid tabulations is subject to change pending math review, analysis of all bids, and review of documentation provided.

Bids: All bids estimated at $25,000 or more are publicly opened and read at the time, date, and place specified in the bid document.

RFP/RFQ/RFI: Responses to RFP/RFQ/RFI are not publicly opened. Names of respondents will be made available based on the names identified on the sealed package and is, therefore, subject to change.

Assessment Appeals by Town and Class from Tax Year 2010.

¹ Includes Sales Tax previously allocated to JTDC for FY08--9. Reflects rate reduction for last 2 months of FY10, last 8 months of FY12 and FY13
² Provided for comparison purposes to revenues as shown in Revenue Estimate
³ Sources: FY07-FY11 from Budget Citizen's Summary, Q-1 Total General Fund Expenditures. FY13-16 based on FY12 with 3.2% annual growth (10 year CPI-U-2.44%/Health-8%).

Single and multi-family (less than 7 units) property characteristics collected and maintained by the Assessor's Office for all of Cook County, from 1999 to present. The office uses this data primarily for valuation and reporting.

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.

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.

This data is improvement-level - 'improvements' are individual buildings on a parcel. Each row in a given year corresponds to a building e.g. two rows for the same parcel in one year means a parcel has more than one building.

Data will be updated bi-weekly. Rowcount and characteristics for the current year are only final once the Assessor has certified the assessment roll for all townships.

Depending on the time of year, some third-party and internal data will be missing for the most recent year. Assessments mailed this year represent values from last year, so this isn't an issue. By the time the Data Department models values for this year, those data will have populated.

NOTE: The Assessor's Office has recently changed the way Home Improvement Exemptions (HIEs) are tracked in its data. HIEs "freeze" a property's characteristics for a period of time with the intention of encouraging owners to improve their property without fear of assessment increases.

Historically, the updated, "improved" characteristics were saved in a separate file. However, in more recent years, the improved characteristics are saved in the main characteristics file. As such, the records in this data set from before 2021 do NOT include HIE characteristic updates, while those after and including 2021 DO include those updates.

For more information on HIEs, see the Assessor's Data Department wiki.

For more information on how this data is used to estimate property values, see the Assessor's residential modeling code on GitHub.

Township codes can be found in the legend of this map.

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 2013 feature contains tax parcel polygons for the 2013 property tax assessment at the County. This feature reflects tax parcel polygons as they existed from 1/1/2013 through 12/31/2013. Each parcel is uniquely identified with a Property Index Number (PIN).

The Street Midlines in this feature class represent the interpreted midline between the compiled edges of pavement. Unimproved rights-of-way are also included in this database.

The Lakes and Rivers hydrographic polygon data layer was created to accurately depict the location and shape of flowing water features greater than five feet in width and major standing water bodies in Cook County.