Tax analytics show county government who’s gaming the system

New policies and data tools are helping Cook County, Illinois, enforce tax codes and recover tens of millions in losses and unpaid taxes.

Chicago’s Cook County is cracking down on property tax evasion with a new analytics system that scours government databases to find where residents are really living.

Officials from the Assessor’s Office report that the county has recovered more than $26 million in losses with the new tool and has billed residents for nearly $46 million in exemption savings to which they were not entitled. For years, residents had been claiming property exemptions on multiple homes, an evasion tactic that had cost the county and community services millions, said Tom Shaer, Cook County deputy assessor for communications.“What we’re tracking down are exemptions that people shouldn’t have and the basic tenet of the exemption laws in Illinois are very simple,” Shaer said. “You only get them on one home and you have to be the primary owner and occupant in that home.”

Shaer credited the recovered funds to a cocktail of policymaking and digital expertise. In 2013, the County Assessor Joseph Berrios drafted a successful piece of legislation that allowed the county to establish an Erroneous Exemption Recovery Program to target property owners taking illegal tax breaks on multiple homes. Shaer said the legislation was groundbreaking in its ability to unshackle county investigators and prevent fraud.

“Prior to early 2013, there was no law allowing us to even go after this lost revenue,” Shaer said. “Assessor Berrios crafted this legislation, proposed it and got it through the Illinois General Assembly to make it a law which allows us to get the money.”


Tim Monahan, the deputy assessor for Erroneous Exemptions, heads a six-person investigation unit responsible for the recovery effort. Monahan said that without the analytics system, developed by business research firm LexisNexis, his team of former police officers would never have had the resources to effectively cover the 1.4 million residential properties in Cook County. The system has saved hundreds man hours, he said.

“The time savings is immeasurable,” Monahan said. “Otherwise it would require phone calls to all these foreign jurisdictions [other states, counties and cities] to see whether or not someone owned property in that particular jurisdiction.”

Users of the system can input different names for the same person, social security numbers and other identifying information and cross-reference it with more than 20,000 public and proprietary databases, providing investigators a peripheral view of homeownership inside and outside the county. The system automatically flags probable cases of exemption fraud for Monahan’s team to investigate. 

“It’s an investigative tool that helps us to figure out an exact address using someone’s driver’s license, his various addresses, or past addresses,” Monahan said. “We have access to social security numbers and we also have access to friends, relatives and neighbors, so it allows us to pinpoint a person to particular location.”

The funds gathered by the program are being funneled back into the community.


“Communities love the [the recovery work] because Assessor Joe Berrios is returning this money directly to them,” Monahan said. “The school districts and the other taxing bodies and other local community groups are ecstatic because this is money that would have been gone forever. Plus, we don’t just recover the lost money but we prevent further loses on the same erroneous exemptions.”

County Budget Director Tanya Anthony said in a statement that the program “has been one of the shining examples of operational efficiency.” Berrios said the combination of policy and tech is something that, in the end, will have perpetual benefit to local communities.

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