Section 140(5)(b) in The West Bengal Panchayat Act, 1973
(b)Notwithstanding anything in this Act, every Zilla Parishad constituted under this sub-section shall be deemed to have been duly constituted in accordance with the provisions of this Act and shall come into office with effect from the date of its first meeting at which a quorum is present, and the Zilla Parishad of the former district shall with effect from the date of coming into office of the newly constituted Zilla Parishads, cease to exist.