Answer
(Fatwa: 636/537/B=1432)
(1) Yes, you can pay income tax with interest money.
(2) Whatever extra amount is received in provident fund is not interest rather it is gift that the government presents to the employee on his good service. It does not fall under the category of interest.
(3) It is not right if one opens fixed deposit in order to receive more interest money. However one can keep money in the bank with the intention of safety and can pay income tax with the interest money received from bank.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband