Since income tax is an unjust and unnecessary tax hence you may use the interest money received from government banks to pay it. It is lawful as it is like returning towards the owner of the money which is the first use of such haram and malicious money. It will not be considered using in personal needs. Thus it shall in no way be lawful to use the interest money in one’s personal use such as to buy a car or fulfil any household requirement with it. However, if any person is extremely poor and needy then it is lawful for him.
Allah knows Best!
Darul Uloom Deoband