The ex-managers, who came forward as part of an effort backed by worker advocacy group Fast Food Forward, said they engaged in tactics such as asking employees to continue working after they clocked out or adding unpaid breaks to time sheets. They took the steps to avoid exceeding a store's strict goals for wage expenses, said Lakia Williams, a former assistant manager at a McDonald's in Charleston, South Carolina.

"There was so much pressure," she said in an interview. "It's not only the franchisees group and the general managers, it is corporate. It's something internal, it's something deeper, and it's something that has been going on for years."

Williams said she would ask employees to work for an hour or two after they clocked out. She needed them to help clean up after a busy day and would usually give them $20 of her own money to compensate, Williams said. Kwanza Brooks, a manager who worked at McDonald's stores in North Carolina and Maryland, said she amended time sheets to keep labor costs down.