Section 180(2) in The Madurai City Municipal Corporation Act, 1971
(2)All money paid into the sinking funds shall, as soon as possible, be invested by the Commissioner in-(a)securities of the Government or the Central Government; or(b)securities guaranteed by the Government or the Central Government;(c)any municipal debenture of Tamil Nadu,and shall be invested in the joint names of the Secretary to the Government of Tamil Nadu, Finance Department and the Examiner of Local Fund Accounts, Tamil Nadu to be held by them as trustees for the purpose of repaying at due date the debentures issued by the corporation. Every such investment shall be reported by the Commissioner to the council within fifteen days.