Section 68(1) in The Representation of the People Act, 1951
(1)Any person who is chosen a member of both the Houses of the People and the Council of States and who has not taken his seat in either House may, by notice in writing signed by him and delivered to the Secretary to the Election Commission within ten days from the date, or the later of the dates, on which he is so chosen, intimate in which of the Houses he wishes to serve, and thereupon, his seat in the House in which he does not wish to serve shall become vacant.
