In many practical cases of alloy processing, the evolution of microstructure is strongly controlled by interfaces and their properties. This applies to phase transformations in steel, such as the austenite decomposition, as well as to, for instance, recrystallization, which can be substantially slowed down by the solute drag-effect. Both features are controlled by the amount of segregation of solute atoms into the defects as well as the site competition favouring the segregation of certain elements over others. In the present work, the original trapping model published in Ref. [1] is adapted to comply to the multi-sublattice structure of the Compound Energy Formalism (CEF) typically used in the CALPHAD approach [2]. The model is incorporated in the MatCalc software package [3]. Some selected application examples are presented and discussed, where the predictions of the model are compared to experimental data from literature. REFERENCES [1] S. Leitner, W. Ecker, F.D. Fischer and J. Svoboda. Thermodynamic trapping and diffusion model for multiple species in systems with multiple sorts of traps. Acta Mater., Vol. 233, pp. 117940, 2022. [2] Hans Leo Lukas, Suzana G. Fries and Bo Sundman, Computational Thermodynamics: The Calphad Method, Cambridge University Press, 2011. [3] https://matcalc.at