In the title mol-ecule, C(9)H(9)NO(3)S(2), the essentially planar benzisothia-zole ring system and the C-S-C atoms of the methyl-sulfanyl side chain form an angle of 64.45 (7)°. The structure is devoid of any classical hydrogen bonding. However, weak non-classical inter- and intra-molecular hydrogen bonds of the type C-H⋯O are present.