First principle calculations of the electron and positron band structures are performed for the SiC polytype of the 3C cubic structure. The perfect and vacancy containing elements are considered. The supercell model is incorporated Electron and positron densities as well as the positron lifetime are determined for the Si and C point defects. The resulting characteristics are studied with respect to their counterparts in the perfect crystal. Various approximations to the electron-positron correlations are applied in the calculation of the positron distribution and lifetime. Importance of non-local effects is emphasized.