BOSTON -- A "software-related calculating error" caused the MBTA to overpay 353 green line employees by $237,433, Team 5 Investigates reported Thursday.

The mistake was caught during a routine review of employee payroll data by the T, according to spokesman Joe Pesaturo.

More than 7,000 checks were recently sent to compensate employees for $42 million in retroactive pay. Most of the checks were accurate, but 353 employees were overpaid by 20 to 30 cents per hour. The overpayments range from $47 to $1,314 per individual.

Pesaturo said after negotiating with the carmen's union, employees are now in the process of paying back the MBTA via weekly paycheck deductions.

A weekly deduction of $25 from each paycheck is being taken until each of the 353 employees has paid back the agency.

This is the most recent financial setback for the troubled transit agency. In April, MBTA General Manager Dan Grabauskas announced a plan to cap salaries, institute mandatory furloughs and lay off at least 75 employees in order to get a handle on the agency's mounting debt that is now estimated at $8 billion.

The T is also looking to raise fares system wide. Service reductions are also being considered, including the elimination of several bus routes with low ridership and a 50 percent reduction in all weekday bus service after 8:00 p.m.

The proposed fare hikes and service cuts would bring the MBTA $124 million in revenue and savings.