Legacy’s successor, Progressive Emergency Physicians, is using the staffers' back pay as a retention bonus, promising it in increments in the first six months of a new contract that offers a 20 percent lower hourly rate than Legacy’s, according to four of the former ER staffers who were offered the deal. The agreement also extends the at-will period at which a doctor can be fired to six months, and stipulates that the retention bonus must be paid back by the employee if he or she leaves within a year, the staffers said.