To claim the refund of tax already deducted by the bank, it is necessary to file her income tax return (ITR). Please note that your mother cannot file her ITR in case she does not have a PAN. Since your mother does not have a PAN, first of all you have to apply for a PAN. However, in case she has an Aadhaar Number, the same can be used in place of PAN to submit an ITR. The same can be furnished to the bank with a request to revise the TDS return submitted by them to mention PAN/Aadhaar number against her name. Unless the bank carries out this correction, your mother will not get credit for the tax deducted by the bank. Moreover, even if your mother submits From 15H, she has to furnish her PAN/Aadhaar, else the bank will again deduct 20 per cent tax on the whole of the interest. Please note that it is not mandatory for you to file your income tax return in all cases where the person has a PAN.