A boom in companies trying to cut costs by contracting out janitorial and security jobs has led to large pay disparities between workers doing the same jobs, according to a UC Berkeley report. Janitors who work for California contractors earn on average $10.31 an hour, or 20% less than janitors who work directly for a company that uses their services, according to the report, prepared by the university’s Center for Labor Research and Education and released Tuesday. … Many contractors, especially smaller companies, also do not pay overtime or even minimum wage, Hinkley said. They often misclassify workers as independent contractors, thereby avoiding making Social Security contributions and sometimes even pocketing taxes that would normally be deducted from paychecks. … When workers want to complain, an often complicated layer of contractors and subcontractors obscures who is responsible for their paycheck and working conditions, Narro said. Many contractors who are hired to supply janitors or security guards will in turn outsource those jobs to subcontractors, which can be “fly by night” operations that work with no contracts, he said.