A Massachusetts firm that provides staffing and contract cleaning services must pay more than $1 million to 149 low-wage workers following a consent judgment in U.S. District Court, the U.S. Department of Labor announced Thursday.

In addition, Ward’s Cleaning Service Inc. of Peabody, Mass., must pay $163,900 in civil penalties and make changes to its payroll system.

Ward’s failed to pay overtime and concealed nonpayment by directing employees to use multiple timecards with different names, altering timecards, paying employees with checks made out to false names and paying employees in cash, the Department of Labor’s Wage and Hour division reported.

“These vulnerable employees were denied their rightfully earned wages through the use of sophisticated schemes to reduce or eliminate the company’s overtime obligations,” said Michael Felsen, the department’s regional solicitor of labor for New England. “This was not the first time; a 1993 Wage and Hour Division investigation of this company found similar violation, which led to workers receiving $172,000 in back wage then.”

Ward’s will have to hire an independent consultant to create a new payroll system as part of the judgment. Ward’s must also submit quarterly reports to the Wage and Hour Division.