The asymmetric unit of the title salt, 2C(17)H(21)N(2)O(2)S(+) -C14H14O7P22-, contains half of a centrosymmetric bis(4methoxyphenyl) diphosphonate anion and one 2-amino-5benzyl-3-ethoxycarbonyl-4,5,6,7-tetrahydrothieno[3,2-c] pyridin-5-ium cation. In the anion, the O atoms of the diphosphonate group are disordered over two positions with equal occupancies. In the cation, the ethyl group is disordered over two orientations with a refined occupancy ratio of 0.753 (5):0.247 (5), and the tetrahydropyridinium ring adopts a distorted half-chair conformation. In the crystal, the ions are linked by C-H. . .O, N-H. . .O and C-H. . .S hydrogen bonds into a three-dimensional network.