In the title compound, C(19)H(12)Cl(2)N(2)O(5)S(3), the benzene rings of the chloro-phenyl-sulfonyl groups form a dihedral angle of 35.85 (8)° and are inclined at angles of 23.51 (6) and 59.22 (6)° with respect to the essentially planar benzisothia-zole ring system [maximum deviation = 0.030 (2) Å]. The mol-ecular conformation is stabilized by an intra-molecular C-H⋯O hydrogen bond. In the crystal packing, mol-ecules are linked into chains parallel to the a axis by inter-molecular C-H⋯O hydrogen bonds and π-π stacking inter-actions, with centroid-centroid distances of 3.592 (5) Å.