That's according to the Cook County treasurer.
Maria Pappas said many people in the south suburbs saw their tax bills jump thousands of dollars this year.
An office analysis shows nearly 13% more residents didn't pay on time after this jump.
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South suburban seniors, in particular, seemed to have had a hard time paying, Pappas said in a news release Wednesday.
Lack of payment can put an owner's home at risk.
The annual tax sale is held about 13 months after the property tax due date.
Visit www.cookcountytreasurer.com for more information.