Section 26(2)(a) in Kolkata Municipal Corporation Building Rules, 2009
(a)if during erection or execution of work any internal alteration within the sanctioned covered space which does not-violate the provisions of the Act or these rules is intended to be made, the person referred to in sub-rule (1) of rule 4 shall inform the Municipal Commissioner by notice in writing alongwith a certificate from the Architect or the Licensed Building Surveyor and Structural Engineer, as the case may be, together with drawings incorporating the deviations, and structural calculation in case of structural deviations, stating the nature and purpose of such deviations, at least fifteen days prior to carrying out such erection or execution of work and may thereafter proceed with the execution of such work, subject to the condition that such deviations shall be incorporated in the „Completion Plan 1 under sub-rule (2) of rule 27;