Republic Acts - An Act to Extend the Effectivity of Republic Act Numbered Five Hundred and Eighty-Nine, by Further Amending Section Seven Thereof, Entitled "An Act to Amend Sections One Hundred and Thirty-Three, One Hundred and Thirty-Four, One Hundred and Thirty Five, One Hundred and Thirty-Seven, One Hundred and Forty, and One Hundred and Forty-Seven of Commonwealth Act Numbered Four Hundred and Sixty-Six, Otherwise Known as the National Internal Revenue Code, as Amended"