A coupling plate (10) for a semitrailer coupling device (20) is described, wherein the coupling plate (10) on a top side (11) comprises a planar bearing surface (12) and at a rear end (13) it comprises two entrance horns (15) bordering on an entrance opening (14), the entrance opening (14) extends in a longitudinal axis (x) of the coupling plate (10) and ends in a kingpin bearing region (14a), andthe coupling plate (10) is configured with a respective receiving structure (17) for a bearing block (21) on its bottom side (16), on either side of the kingpin bearing region (14a) and spaced apartfrom each other on a transverse axis (y). The problem which the invention proposes to solve is to provide a standardized coupling plate (10), having a minimal natural weight, given a slight loading, and whose strength can be adapted for higher anticipated loads. The problem is solved according to the invention in that at least one connection means (30a, 30b, 30c) for the releasable mounting of atleast one stiffening element (40a, 40b, 40c) is formed on the coupling plate (10) beneath the planar bearing surface (12).