Employee is drawing more than 15000/- e.q. Rs. 20,000/- then is it mandatory for an employer to deduct EPF on 15000/-?

As per the Act the employer has to deduct and deposit EPF amount @12% of Basic Pay for an employee whose salary is upto 15000/-
If an employee is drawing more than 15000/- e.q. Rs. 20,000/- then is it mandatory for an employer to deduct EPF on 15000/- and deposit the share of employee and employer ??

yes, based on mutual understanding the establishment may maintain the ceiling limit of 15000/- or pay both contributions on the whole 20000/- but once enrolled in EPF it can not be avoided