Nagapattinam was declared a municipality in 1866 during British times. It was promoted to a second grade municipality in 1986 and selection grade in 1998. From 1991, the municipal limits were expanded to include Nagore. The municipality has 36 wards and there is an elected councillor for each of those wards. The functions of the municipality are devolved into six departments: General administration/personnel, Engineering, Revenue, Public Health, Town planning and IT. All these departments are under the control of a Municipal Commissioner who is the supreme executive head. The legislative powers are vested in a body of 36 members, one from each of the 36 wards. The legislative body is headed by an elected chairperson, assisted by a deputy chairperson. The town became the district headquarters when the Nagapattinam district was created as a separate district.