In the molecule of the title compound, C16H12ClF3N2O4S, the thiadiazine ring adopts a half-chair conformation. The dihedral angle between the benzene ring of the benzothiadiazine ring system and trifluorophenyl group is 15.02 (7)°. In the crystal, centrosymmetrically related molecules are linked into dimers via pairs of O—H⋯O hydrogen bonds, generating R
2
2(8) ring motifs. The dimers are further connected into a three-dimensional network by C—H⋯O hydrogen bonds