Casual vacancies how to be filled up

Casual vacancies how to be filled up. Where a vacancy occurs through the resignation or non-acceptance of office by a person elected to be a councillor, or through such person becoming disqualified to be a councillor, or through any election being set aside under the provisions of section 23 or through the death, removal or disability of a councillor previous to the expiry of his term of office, the vacancy shall be filled up as soon as may be after the occurrence of such vacancy by the election of a person thereto: Provided that no election shall be held to fill a casual vacancy occurring within six months prior to the expiry of the term of office of councillors under sub-section (1) of section 18.