A considerable potential advantage of manufacturing electric and thermoelectric devices using endohedral metallofullerenes (EMFs) is their ability to accommodate metallic moieties inside their cavities. Published experimental and theoretical works have explained the usefulness of this resilience feature for improving the electrical conductance and thermopower. Through thorough theoretical investigations of three EMF complexes employing three different metallic moieties involving Sc3C2, Sc3N, and Er3N and their configurations on a gold (111) surface, this research demonstrates that the thermoelectric properties of these molecular complexes can be tuned by taking advantage of the charge transfer from metallic moieties to Ih-C80 cages. Mulliken, Hirshfeld, and Voronoi simulations articulate that the charge migrates from metallic moieties to cages; however, the amount of the transferred charge depends on the nature of the moiety within the complex.