The mean average errors of solvation free energies of ions computed using models such as COSMO-RS and Solvation Model based on Density (SMD) 116 have been shown to exceed 4 kcal mol -1 , which can be reduced to approximately 2 kcal mol -1 if a systematic correction term is included. To correct for systematic offsets (from misalignment of energy scales and also from solvation model error), we first determined the systematic offset parameters δ that would minimize the mean squared error of the predictions for each solvent using D2A-dGsolv-anion/train. These values are then added to the COSMO-RS predictions and compared to D2A-dGsolvanion/test. Benchmarking results are shown in the SI.