Section 57(3)(a) in Tamil Nadu Town and Country Planning Act, 1971
(a)the appropriate planning authority may serve a notice on the owner requiring him within such period, being not less than seven days to remove that part of the building built subsequent to the notice served under sub-section (1). If, the direction is not complied with, within the period specified therein, the appropriate planning authority may demolish that part of the building built subsequent to the notice served under subsection (1) and reserve the right to recover the cost of any expenses incurred by it in this behalf from the owner, as an arrear of land revenue.