The Greenfield School District will ask employees to pay back more than $25,000 that should have been withheld from paychecks in 2011, the Greenfield School Board learned Monday.

A change in state law in 2011 that made it illegal for employers to contribute to the Wisconsin Retirement System on behalf of their employees resulted in the withholding mistake.

According to a tax lawyer who addressed the board Monday, the “under withholding” issue inadvertently occurred for four quarters, starting in August 2011. The district paid the withholding difference for the last two quarters of 2011; employees paid it during the first two quarters of 2012.

The district will ask employees to return the equivalent of 1.6 percent of the payroll spending, or roughly $70-100 per employee.

“It’s taxpayer money and we want to recoup that money, at least I do,” School Board president Bruce Bailey said. “It is taxpayer money that was under-withheld. … We need that money back.”

Employees who are still with the district will be able to work out how the money is remitted during upcoming pay periods. Employees not part of the district will be asked to return the money.