2006 New York Code - Change Of Occupancy Or Use.

 
    §  27-217  Change  of occupancy or use. (a) No change shall be made in
  the occupancy or use of an existing building which is inconsistent  with
  the  last  issued  certificate  of occupancy for such building, or which
  would bring it under some  special  provision  of  this  code  or  other
  applicable  law  or regulation, unless a new certificate of occupancy is
  issued by the commissioner certifying that such building or part thereof
  conform to all of the applicable provisions of this code and  all  other
  applicable laws and regulations for the proposed new occupancy or use.
    (b)  Except  as  provided by law, a new certificate of occupancy shall
  not be required where the change of use is within the same use group  as
  listed  in the amended zoning resolution. Where a building exceeds three
  stories in height and the change does not exceed twenty per cent of  the
  total  floor area, an amendment to the existing certificate of occupancy
  for such new use shall be issued by the commissioner certifying that the
  proposed new occupancy and use conforms to the provisions  of  the  laws
  governing building construction and that the proposed use will not be in
  conflict  with any provisions of the labor law, multiple dwelling law or
  the zoning resolution.