Metropolitan Water Reclamation District Commissioner Patrick Daley Thompson – the grandson of late Mayor Richard J. Daley and a nephew of retired Mayor Richard M. Daley – has owned his family’s ancestral Bridgeport home for a decade, since his beloved grandmother Eleanor “Sis” Daley died there in 2003.

The tidy bungalow at 3536 S. Lowe was the center of Chicago’s political universe for years before – as the place where the first Mayor Daley lived and raised his clan.

Now the building is the center of a controversy, amid findings from the Better Government Association and CBS2 that Thompson benefitted from property tax breaks on that home and another property when only one tax break was legally allowed.

3536 S Lowe + CBS 2
​Thompson home at 3536 S. Lowe / CBS2

Thompson, the only member of the family’s third generation to enter electoral politics, said he only learned about the dual “home owner exemptions” after inquiries from a reporter to the Cook County treasurer’s office.

He portrayed the double tax breaks as an honest mistake, although he indicated he’s not sure how the mistake happened. Thompson, 44, said he never filed for or even knew about the erroneous exemptions until now, and that his lender handles his property taxes. Either way, Thompson quickly cut a check for roughly $11,600 – the amount in property taxes he improperly saved over the last decade.

“I’m a little baffled,” Thompson said. “Sometimes there’s a clerical error.”

A home owner exemption is designed to ease the property tax burden on a primary residence and by law can’t be used on rental or investment property.

If you don’t see the video above, click here and watch it on CBS2.

But Thompson had two exemptions dating to 2002, according to Cook County property records. At that time he owned a home on the 3800 block of South Parnell and a two-flat on the 3500 block of South Lowe, records show. Both were getting tax breaks.

Then in 2003, he bought his grandparents’ house on Lowe, sold the Parnell property and kept the Lowe two-flat. Since then, he’s gotten a tax break on both Lowe properties, Thompson confirmed.

Over the past year, the BGA has reported that several politicians and employees of the Cook County assessor’s office – which issues property tax exemptions – were improperly receiving more than one tax break. They include Cook County Treasurer Maria Pappas, state Rep. Luis Arroyo (D-Chicago) and former Sauk Village Mayor (and current assessor employee) Lewis Towers.

Patrick Daley Thompson check + public domain
A check Thompson wrote to cover his erroneous home owner exemption for the 2004 tax year.

In July, Gov. Pat Quinn signed a bill that allows Assessor Joe Berrios’ office to start pursuing anyone receiving erroneous exemptions and collect back taxes. In the past the assessor only had the power to cancel improper exemptions. An amnesty period runs through the end of the year for those with two or fewer improper exemptions.

The assessor’s office estimates that improper tax breaks – received accidentally or otherwise – total roughly $65 million a year, a cost that’s ultimately covered by other taxpayers.

The average Cook County home owner exemption this year is worth about $450, according to Berrios’ office.