Roland Herzog, TU Chemnitz, Chemnitz, Germany Joint work with Juan Carlos de los Reyes and Christian Meyer Elastoplastic deformations play a tremendous role in industrial forming. The optimization of such problems is therefore of interest not only mathematically but also for applications. In this talk we will consider a basic model of static elastoplasticity in its so-called primal (strain-based) and dual (stress-based) formulations, which are known to be equivalent. Since the primal model involves a variational inequality of the second kind and the dual model includes a complementarity condition, associated optimal control problems have an MPEC or MPCC structure, respectively. Consequently, the derivation of optimality conditions is more involved than for smooth nonlinear optimization problems. We will derive such optimality conditions by a limiting process for both concurrent formulations and show their equivalence.