law: 20. Oath of office. 
  (1) Every person who is elected or appointed as a Councillor of a municipality shall, before entering upon his office under this Act, make and subscribe before such authority as may be prescribed for the purpose, an oath or affirmation of his allegiance to the Constitution of India in the prescribed form.
  (2) Any person, having been elected, or appointed as a Councillor fails to make and subscribe, within three months from the date of the first meeting of the municipality the oath or affirmation laid down in sub-section (1) shall cease to hold his office and his office shall be deemed to have become vacant.