Density functional theory calculations are implemented in order to scrutinize indium adsorption and incorporation mechanisms in polar AlN. Indium adsorption is promoted on both polarity surfaces and adatom kinetics calculations indicate lower diffusion barriers of indium along the prismatic aOE (c) directions of the pyramidal facets. Surface thermodynamics reveal a manifold behaviour of indium in polar AlN surfaces, significantly affected by polarity, growth stoichiometry as well as surface termination. In particular, N-rich growth conditions enhance indium incorporation on Al-terminated surfaces of both polarities, leading up to full monolayer coverage. Incorporation on N-terminated (0001) and () surfaces is hindered independent of growth stoichiometry.