Sound evaluation of soil damping is of great importance for the optimised design of offshore wind turbine support structures. As practice indicates, design optimisation of the support structure often leads to fatigue-driven structural components, especially at the monopile foundation. Saving steel material is important for the economic feasibility of the project, while satisfying fabrication, transportation, and installation requirements. Conventionally, the baseline/background damping consists of steel material, hydrodynamic and soil damping. Design experience indicates that soil damping contribution to the overall baseline damping is significant, especially in case of strong non-linear soil response. This study employs an analytical and a numerical method to evaluate soil damping under realistic project conditions. Results indicate that the analytical method offers a sound basis for fatigue-oriented soil damping assessments, especially at the initial stages of the project.