Constitution of India, 1949
65. The Vice-President to act as President or to discharge his functions during casual vacancies in the office, or during the absence, of President.-
(1) In the event of the occurrence of any vacancy in the office of the President by reason of his death, resignation or removal, or otherwise, the Vice-President shall act as President until the date on which a new President elected in accordance with the provisions of this Chapter to fill such vacancy enters upon his office.
(2) When the President is unable to discharge his functions owing to absence, illness or any other cause, the Vice-President shall discharge his functions until the date on which the President resumes his duties.
(3) The Vice-President shall, during, and in respect of, the period while he is so acting as, or discharging the functions of, President, have all the powers and immunities of the President and be entitled to such emoluments, allowances and privileges as may be determined by Parliament by law and, until provision in that behalf is so made, such emoluments, allowances and privileges as are specified in the Second Schedule.