Potassium polyaspartate (KPA), whose use was approved by OIV in 2016 and regulated by the European Union (Commission Delegated Regulation (EU) 2017/1961, 2017), is a polymer constituted by monomeric L-aspartic acids, synthesized by fermentation process, and used to prevent undesired potassium bitartrate (KHT) precipitation in bottled wines. Calcium L-tartrate (CaT) precipitation has also recently affected bottled wines as an effect of compositional changes due to climate change. Studies on the effect of KPA on it are limited. Based on these considerations, the aim of this study was to evaluate the effect of KPA on the calcium stability of five white and two rosé wines with different calcium and potassium stability conditions. Temperature of saturation for both potassium (T_sat^KHT) and calcium (T_sat^CaT) was determined. KPA addition (100 mL hL^-1) stabilized all unstable T_sat^KHT’s samples. It affected T_sat^CaT, which increased in KPA-added samples. This suggests that CaT nucleation is enhanced by reduced K⁺ availability and by modification of tartaric acid dissociation equilibria. Two static cold tests were conducted; the first test (72 h at -4 °C) showed an increase in Ca²⁺ precipitation in KPA-added samples, and in the second test (72 h at -4 °C; excess of CaT, 4g hL^-1), Ca²⁺ was not affected by KPA addition, while K⁺ precipitation increased. CaT affects KHT stability in the presence of excess of CaT; this effect was confirmed by Scanning Electron Microscopy analysis (SEM) with element analysis. In conclusion, KPA could induce nucleation, favouring CaT precipitation during cold tests, and in the presence of excess of CaT it facilitates ionic disequilibria, making it more difficult to manage the precipitation of CaT and KHT salts over time.