Section 43D(2) in The U.P. Municipalities Act, 1916
(2)The President or the members who fails to make, within three months of the date on which his term of office commences or at any one of the first three meetings of the [Municipality] [Substituted by U.P. Act No. 12 of 1994.], held after the said date, whichever is later, unless this period is extended by the District Magistrate, the oath or affirmation laid down in and required to be taken by sub-section (1) shall cease to hold his office and his seat shall be deemed to have become vacant.
