Linear polarization of the multiexciton emission from self-assembled quantum dots is investigated by using an empirical tight-binding method. The polarization of the primary interband transition is shown to have a quadratic dependence on the lateral aspect ratio of the structures and is insensitive to both the excitonic and random intermixing effects, which make it an appropriate tool for structure characterization. The ground-state transitions in the emission spectra of multiexciton complexes are found to exhibit very different polarization from the primary interband transition, which we attribute to different component profiles in the excited valence-band states.