Section 273A(4) in West Bengal Municipal Corporation Act, 2006
(4)The Corporation shall be the authority to issue permission to the owner or licensee to carry out non-hazardous trade or office in a part of the residential building, directly, or through sub-lease or letting. On the basis of self declaration of the owner or lessee of the residential building, and submission of requisite fees, permission will be granted by the Corporation to the owner or original lessee or original sub-lessee as the case may be, immediately, as per law.