In the title compound, [Sn(CH(3))(3)(C(7)H(2)Cl(3)O(2))](n), the tin(IV) atom exhibits a slightly distorted trigonal-bipyramidal geometry with two O atoms of symmetry-related carboxyl-ate groups in the axial positions and three methyl groups in the equatorial positions. In the crystal structure, the metal atoms are linked by carboxyl-ate bridges into polymeric chains extending along the b axis.