In this work we consider orthogonal polynomials via cubic decomposition in the framework of the third degree semiclassical class. Based on their third degree character, we give a complete description, by using the formal Stieltjes function and the moments, of semiclassical linear forms of class two arising from the cubic decomposition W3n(x) = Pn(x3); n ≥ 0. We focus our attention on the link between these forms and the strict third degree classical forms Vqk,l= J (k + q/3; l -q/3), q ∈{1,2},k,l ∈Z with k+ l≥ -1. All of them are rational transformations of the Jacobi form V = J (-2/3;-1=3).