We have performed first-principles calculations for all the differently terminated three low-index surfaces of CoSb3 skutterudite. Surface energies, lattice structures and electronic structures have been investigated applying different functionals within the plane-wave density functional theory. Each functional consistently reveals the (110) as the most stable surface, followed by (100) and (111), respectively. For each surface plane we have studied all possible terminating surface layers and a structural comparison shows that the surface stability is mostly determined by the Sb4 subunits. Wherever complete Sb4 subunits remain intact at the surface the stability is high. For the most stable surfaces, we have calculated the surface band structure in reference to the projected bulk band continuum and identified surface states. These surface states promote the metallic character at the CoSb3 surfaces. The freedom of spin polarization leads to a magnetic configuration in the (110) case.