The structural analysis of the title compound, C14H14N2O4S, particularly the presence of an acetyl group at the exocyclic N atom and the C(H)-C(O2CMe)-N acet-oxy group in the thia-zole ring, may indicate that one of the starting materials, i.e. 2-(4-meth-oxy-anilino)-1,3-thia-zol-4(5H)-one, exists in the reaction mixture, at least partially, as a tautomer with an exocyclic amine N atom and an enol group. The acet-oxy and acetyl groups deviate from the thia-zole plane by 69.17 (6) and 7.25 (19)°, respectively. The thia-zole and benzene rings form a dihedral angle of 73.50 (4)°. In the crystal, centrosymmetrically related mol-ecules are connected into dimeric aggregates via C-H⋯O inter-actions.