In support of this, the following lines have been picked up from the FAQs of EPF website:-
24) What is the voluntary rate of Provident Fund contribution by the member?
As per the Act, the member has to contribute at the rate of 10% or 12% of his basic pay, D.A. & retaining allowance if any. In case the member wants to contribute more than this, voluntarily he can do so at any rate he desires. i.e. up to 100% of basic and D.A. But the employer is not bound to contribute at the enhanced rate but only up to the maximum wage ceiling of Rs. 15000/- only.