The aim of this article is to carry out theoretical investigation of the influence of the multiple beam interference on the phase retardation of liquid crystal cells. For the theoretical description of this effect, Heavens-Clarke matrix formalism was utilized. As a result, the significant influence of interference effects on the phase shift of the transmitted light is demonstrated. It is shown that the interference effects are determined by geometrical and optical parameters of the constituting layers of a liquid crystalline cell. Moreover, it is demonstrated that for a given liquid crystal at a given temperature an optimized combination of variable parameters as thicknesses of liquid crystal layer, polymer layer, electrode layer, glass substrate layer the influence of the multiple interference on the phase retardation can be minimized.