In the title compound, 2C5H12N+·SO42-·2C3H8N2S, the C=S groups of the two independent 1,3-di-methyl-urea mol-ecules and the sulfur atom of the anion lie on twofold axes. The packing is centred on bis-(piperidinium) sulfate ribbons parallel to the c axis; the cations are hydrogen bonded to the sulfate by N-H⋯O and C-H⋯O inter-actions. The 1,3-di-methyl-urea mol-ecules are also hydrogen bonded to sulfate O atoms, and project outwards from the ribbon parallel to the b axis.