SECTION 1. Section three of Republic Act Numbered Six hundred, as amended by Republic Act Numbered Eight hundred and sixty-eight, is further amended to read as follows:
"SEC. 3. The provisions of this Act shall apply to income received from January first, nineteen hundred and fifty-one to December thirty-one, nineteen hundred and fifty-five, after the expiration of which later date the provisions of sections twenty-four and fifty-four of the National Internal Revenue Code, as amended, shall again be in full force and effect."