In the title compound, C(14)H(17)NO(5)S, the thia-zine ring adopts a half-chair conformation. The mol-ecule exhibits an intra-molecular O-H⋯O hydrogen bond, which forms a six-membered S(6) ring motif. The planes of the benzene and thia-zine rings are inclined at a dihedral angle of 15.30 (12)°.