Fixed Deposit Calculation: Be it a cumulative FD where the interest is paid at the time of maturity or a non-cumulative FD where the interest is paid periodically, you have to pay tax on the interest income of your fixed deposit every financial year. This interest is taxable as per the tax bracket of the investors. Is there a way senior citizens can earn tax-exempted returns from tax-saving FD? How much should a senior citizen invest? ET Wealth Online explains