Atomic energy levels and E2 and M1 transition rates are reported for the [Xe]4f11 ground configuration in Er3+ from relativistic multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations. The Breit transverse interaction and leading QED effects are included as perturbations. Different strategies for describing electron correlation effects are tested and evaluated. The calculated energy levels are compared with experiment and results from semi-empirical methods.