1. IF the Basement is attached to an individuals property (flat, bungalow, row-house or whatever) and the access to the basement is ONLY by an indvidual owner and not by other members of the Society etc...., THEN, the basement is considered part of the individual property and can be used by the owner for semi-commercial activities (like approved consultants, CA's, Advocates, Doctors, Tution etc...), without attracting commercial property taxes, commercial electricity rates, commercial water rates.
2. In the event, IF the whole of the unit (basement + house) is solely used for commercial activities, then appropriate permissions have to be obtained from respective competent authorities, civic authorities, society authorities etc.... and will attract commercial property taxes, commercial electricity rates, commercial water rates.
3. The definations of Commercial vs Residence permissions is an issue covered by local area civic acts and rules, like Development Control rules for apartments, PWD, Sewage dept, and other authorities.
Keep Smiling .... Hemant Agarwal