Notwithstanding anything contained in the Indian Income-tax Act, 1922 (11 of 1922), or in any other law for the time being in force relating to taxation on income, no income-tax or super-tax shall be payable by any person--
         (a) where his salary is paid out of the Consolidated Fund of India or of the Consolidated Fund of a State, in respect of that part of the salary due to him for any period after the 31st day of March, 1961 which he has, by a declaration in writing, volunteered to forego in the public interest;
         (b) in any other case, in respect of that part of the salary which is due to him for any period after the 31st day of March, 1961 which has been, in the public interest, surrendered in favour of, and paid to, the Central Government in accordance with the rules made in this behalf by that Government;
and such part of the salary shall not be included in his total income for the purposes of any law relating to taxation on income.