MedAustron is a hadron therapy facility in Wiener Neustadt, Austria, based on the PIMMS design (Proton-Ion Medical Machine Study). The injector features three Supernanogan ECR ion sources from Pantechnik. One is reserved for proton therapy, one for therapy with carbon ions, and the third one serves as a backup and might be used for clinical and non-clinical research in the future. Patients are being treated with protons since December 2016. In parallel, the carbon ion beam commissioning is ongoing. In this paper results and status of the commissioning of the source for carbon ion beams are presented.