The title compound, C(4)H(12)N(+)·C(8)H(11)NO(5)PS(-), was obtained from tetra-methyl-ammonium hydroxide and dimeth-yl(phenyl-sulfon-yl)amido-phosphate. The tetra-methyl-ammonium cation has a slightly distorted tetra-hedral configuration and the N-C bond lengths lie in the range 1.457 (3)-1.492 (3) Å. In the crystal, no classical hydrogen bonds are observed between the cation and the anion.