Three loops renormalization constants in Numerical Stochastic Perturbation Theory

We present three loops renormalization constants for Wilson fermion bilinears (vector, scalar, axial, pseudoscalar currents). Two gluonic regularizations are considered: tree level Symanzik improved action (with N f = 2) and Iwasaki action (with N f = 4). Both cases are amenable for comparisons with non-perturbative results. We discuss the issue of taming both finite lattice spacing and finite volume artifacts. As a byproduct, we comment on two loops matching of lattice and continuum couplings.