Depositing money into a bank is actually a loan where the bank will use your money to loan out more money to others with interest. This is normally not allowed, but since there is a need for most people to have a bank account, you should open an interest-free one so you do not get any interest income. If that is not possible, then choose an account which gives you the least interest, then dispose of the interest accrued by giving it away in charity whenever you get it with no expectation of any reward. The lower interest accounts prevent the bank from giving out more interest loans, so you do not fuel that economic system more than you have to. If you do not have access to the interest funds immediately, use your own liquid funds to give that money away in charity and keep a record that the interest has been purified from your account.
Shaykh Mustafa Umar