Can anybody guide me what are the Voluntary Provident Fund rules. If possible can you explain with an example?

Dear All, Can anybody guide me what are the Voluntary Provident Fund rules. If possible can you explain with an example?
Thanking you.

For an employee to deduct epf contribution above the ceiling limit its called voluntary deductions.
This however is not the obligation for employer.
To start voluntary deductions the employee along with employer need to submit joint application to epfo office concerned.Once approved then only voluntary deductions can be made.
Employer however can contribute up 13% of the ceiling limit which is 15k.

if suppose can i deduct 20% from employee salary. suppose if employee salary (except HRA) is 100000 then can i deduct 20000 from his salary and pay the employer contribution on 15000. is this acceptable?? can any body explain....