Darryl Lloyd, who purchased his 1950s Chicago Heights home in 2006, was “devastated” to learn that an erroneous property assessment valued his 960 square foot home at over $1 million, when in fact the real value should be around $180,000.

A Cook County Assessor’s Office representative acknowledged the mistake, which involved an incorrectly added permit. Although the appeal deadline has passed, a corrected bill is being processed, Fox Business reports.

Unfortunately, Mr Lloyd’s case is not singular. Thousands more Chicago residents have faced similar property tax errors, according to a Cook County Treasurer’s Office analysis. Over 4,400 homes in the south and southwest suburbs were overassessed due to land value miscalculations.

Analysis from Cook County Treasurer’s Office stated: “The errors were discovered too late in the process for them to be corrected before tax bills were calculated, printed and mailed. The 4,400 erroneous bills were put on hold pending corrections, with the hope they could still be completed by the July 2 mailing deadline.”