I would differ from Raghunath because nowhere in the EPF & MP Act is it stated that PF should be deducted and contributed on the total of Basic and DA if the same exceeds Rs 15,000. The employer and/or employee can very well restrict their contribution to 12% (or such other percentage that the government shall fix) of Rs 15,000. As such, if the sum of Basic and DA exceeds Rs 15,000 or is Rs 17,500, there is no obligation either to the employee or the employer to contribute PF at the rate of 12% of Rs 17,500. But either or both can do it on 12% of Rs 15,000.
If some employees want to contribute on Rs 17,500 or any higher amount like Rs 30,000 or Rs 35,000, they can do so. Even if the employees are contributing on higher salaries, there is no compulsion for the employer to contribute their share on the same salary. At the same time, if the employer's share of contribution is a part of remuneration, as in the case of CTC, wherein whatever cost the employer incurs on an employee will be put as part of remuneration payable, then the employer can also contribute on such higher salaries. (Had it been done earlier, the employee would have gotten the benefit of a higher pension.)
Simply put, an establishment can have different rates of PF, not lower than 12%, and different PF qualifying salaries, say Rs 15,000 or higher than Rs 15,000, for employees and the employer. That is, there can be employees contributing on Rs 15,000 and employees contributing on actual salaries higher than Rs 15,000. There can also be employees in respect of whom the employer is contributing on a salary of Rs 15,000 and employees in respect of whom the employer is contributing on actual salaries that are higher than Rs 15,000.
However, it is advisable to avoid the employer's contribution on different PF qualifying salaries because it may lead to disputes from those employees for whom the employer had restricted their contribution to 12% of Rs 15,000. In fact, a contribution on a higher salary would be part of an understanding between the employees and the employer, and the same is reflected in their CTC and take-home salary. Employees who receive lower amounts as employer contribution may raise it as a dispute in the future. Therefore, it is good to follow the same practice for all employees, either paying it on Rs 15,000 or on actual salaries. Employees can choose either Rs 15,000 or actual salary because it gives them a tax benefit by contributing to PF.