The EPF Act does not mention about 'middle' or 'high' range of salary, but it only says about 'number of employees' and 'amount of salary per month'. As such, establishments employing 20 or more are covered under the Act, and those employees whose salary (basic + DA) at the time of joining does not exceed Rs 6500 are covered. Those whose salary at the time of joining exceeds Rs 6500 can also become members of the PF, but it is not mandatory, which means they can opt out. However, an employee once covered will continue to be covered irrespective of his salary. Therefore, if the company wants to give coverage to all employees, then it should be decided right at the time the PF is enforced; otherwise, it will become mandatory to give coverage in the future. You cannot have two treatments in the same organization like those drawing more salary but with PF and those even though drawing more than the ceiling but without PF.
Regards, Madhu.T.K