Cook County (Illinois) reported thousands of homeowners received erroneous tax delinquency notices, according to the Chicago Sun Times. The issue might have arisen because of data errors in a data set provided by CoreLogic, according to a source with knowledge of the discrepancies.

First installment tax bills went out to Cook County property owners earlier in March, but thousands of people also got notices from their bank demanding payment on tax bills they paid last year, based on a computer glitch.

The erroneous notices went out to home mortgage customers warning the homeowners owe money on their second-installment property taxes, which were due in December. Some notices said the homeowner’s bank would pay the delinquent balance and then assess fees and interest to the customer.

The notices began arriving days ahead of the Cook County treasurer’s office mailing first-installment bills for 2022, likely adding to the confusion.

California-based CoreLogic says it offers “near real-time data” from 22,000 taxing authorities nationwide. The newspaper stated CoreLogic did not respond to questions.

“If a property has no outstanding tax bill, the delinquency notifications should not have triggered any payments by banks because the treasurer’s office bounces back overpayments,” Andrew Gavrilos, spokesman for Cook County Treasurer Maria Pappas, said. “If we had gotten a payment on a property that did not owe taxes, we would not have let that payment go through.”

Chase Bank, the largest mortgage lender in Cook County, reported 4,000 customers erroneously got letters warning of nonexistent tax delinquencies. The bank told customers affected by the error to disregard the delinquency notices, according to spokesman Brian Hanover.

“Due to a system timing issue, a number of Cook County property tax accounts were incorrectly identified as delinquent, which may have triggered a letter to those taxpayers by their lender,” Hanover said. “We fixed the issue, and no further action is required by our customers.”

Other major mortgage lenders did not respond to questions about whether their customers got similar notices, including CitiBank, Bank of America and Guaranteed Rate.