The amount which the government deducts on percentage basis from monthly salary in the name of provident fund and adds the same amount from its side in the name of interest, it is not interest as a matter of fact, rather it is gift for the good services of the employee. Hence you are allowed to take that extra amount.
But it will not be right for you to take interest on that extra amount which you get deducted willingly on your behalf. Whatever amount the government will add it shall be interest which should be given by you in charity.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband