In the title compound, C(10)H(11)N(3)O(2)S, the thia-zine ring exists in a conformation inter-mediate between twist-boat and half-chair. The dihedral angle between the mean plane of the thia-zine ring and the hydrazide group is 89.45 (13)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into (100) sheets and weak C-H⋯O inter-actions further consolidate the packing.