SECTION 1. Section seven of Republic Act Numbered Five hundred and sixty-seven, as amended by Republic Act Numbered Seven hundred and twenty-five, and Republic Act Numbered Eight hundred and seventy, is further amended to read as follows:
"SEC. 7. This Act shall take effect upon its approval, but, unless otherwise expressly extended by Congress, the increased taxes provided for in this Act shall continue in force and effect until December thirty-one, nineteen hundred and fifty-five."