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Cook County – Integrated Property Tax and Mass Appraisal System
DTI’s Roles


At the peak time of the project, DTI provided over 30% of the system integration work and project management support. DTI’s main project responsibility is in data conversion, including developing the software to convert the records of the 1.8 million parcels going back twenty years.


Based on the strong performance of DTI on this project and the growth of iasWorld® in the marketplace, Tyler Technologies added 18 DTI developers to Tyler Technology’s development centers to support other projects. They also brought on-site DTI consultants to perform specific roles on two other iasWorld® projects:


  • City of New York – performance testing, and

  • City and County of Denver, CO – project management support.


Industry / Customer Profile

SLED / Large County


IT Consulting - Enterprise Solutions, Digital Transformation, Advisory - Project Management Office (PMO)


Tyler Technologies’ iasWorld® appraisal and tax administration software


System Integrator: Tyler Technologies, Inc.

Software Provider: Tyler Technologies, Inc.


  • Cook County is the largest county to implement Tyler Technologies iasWorld® and the County had requirements that were not met by the baseline product.

  • Twenty years of historical data needed to be converted. The data conversion logic is very complex as there are imbedded codes and data values change meaning over the years.

  •  The project requires the offices of six separately elected county officials to work together and share an integrated system for the first time. With the 2018 election, the County Assessor and the County Clerk, who both were actively involved in the initiation of the project, were replaced.


  • When completed, iasWorld®. will provide a modern solution that will replace property tax systems, some of which were developed in the 1970s, and associated databases. It will simplify workflow and business processes, such as using mobile technology for assessments and appraisals, increase transparency, improve data accuracy and reporting, and provide data analytics. It will also improve assessment, valuation, and collection business processes.

  • A single, real-time, online, integrated system will provide a complete view of each property record and will be used by several County offices and departments, including the Assessor, Treasurer, Clerk, and the Board of Review (formerly the Board of Tax Appeals).

  • The new online system will provide customers, including property owners, attorneys, and taxing districts, with improved access to property tax records through a public portal.


Cook County is the second largest county in the country with a population of over 5 million people. There are 135 municipalities within the county. It collects $12 billion annually.


The legacy processes for managing property taxes for 1.8 million parcels include multiple stand-alone databases, including spreadsheets and Microsoft Access databases, paper forms and multiple complex systems, including systems on the county’s mainframe computers. 


After agreement between the various county offices that are involved in the property tax processes, the County issued a Request for Proposals for the Implementation of a Property Tax and Mass Appraisal System and the re-engineering of related property tax processes. After receiving and evaluating multiple proposals, the County contracted with Tyler Technologies to implement its iasWorld® appraisal and tax administration software solution and replace the County’s existing standalone property tax related systems. The system is scheduled to go-live in 2024.


Because of the size and complexity of the County, and its desire to dramatically improve its efficiency, customizations to iasWorld® will be required. These customizations include functionality related to tax extension, portal, bond, tax redemptions, refunds, and certificates of error.

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