We have studied the additivity of the anion-pi interaction using high level ab initio calculations. We have optimized chloride and bromide complexes with one, two and three aromatic units (such as trifluoro-s-triazine and s-triazine). We have analyzed the interaction using the atoms in molecules theory and studied the charge transfer using several methods for deriving atomic charges. The results revealed additivities of both the geometries and the binding energies. We have also proposed a neutral receptor for chloride based on multiple anion-pi interactions. Finally, we have simulated solvent effects within the self-consistent reaction field model.