An October report from state Comptroller Thomas DiNapoli’s office states that some residents were overcharged for water and sewer penalties in 2017.

In total, customers were overcharged $8,654 in late fees, the report reads. Marlborough bills for water and sewer usage three times a year.

Customers who are late to submit their payments receive a penalty. According to the report, the penalty rate was, “mistakenly set at 20 percent rather than the correct amount of 10 percent.”

In an Oct. 4 letter to the comptroller’s office, Marlborough Town Supervisor Al Lanzetta said the town agrees with the report’s findings and is taking corrective steps.

The supervisor’s secretary, Tina Rosa, said the incorrect penalty rate stemmed from an issue with the billing system, Springbrook. Rosa said she processes the town’s utility billings.

“Without having time or access to research the issues, it’s unclear what would have caused this issue,” said Rick Hajjar of Springbook Northeast.

Marlborough stopped using Springbrook’s software in Oct. 2017, Rosa said, several months before the audit. The comptroller’s audit took place between Jan. 2017 and April 2018. According to the report, customers were overcharged because town officials didn’t realize the error in penalty rates.

Rosa said there were several reasons the town switched software, including unifying the town’s billing systems.

The town is in the process of identifying the residents who were overcharged and applying credit to each customers’ account, Rosa said. There isn’t a timeline for this process but it’s expected to be completed before February.