<p>Small-strain soil stiffness exhibits nonlinear degradation with increasing shear strain and depends on the stress state. While the stress dependency of the small-strain shear modulus is already incorporated in the HS-Small model, the threshold strain parameter γ₀.₇ is typically treated as constant. This study introduces a stress-dependent formulation for γ₀.₇ and evaluates its influence on stiffness degradation and deformation predictions. This study investigated the influence of introducing a stress-dependent formulation for the threshold strain parameter γ₀.₇, while retaining the conventional stress-dependent formulation for G₀ within the Hardening Soil–Small constitutive framework, with particular emphasis on the combined influence of stress-dependent small-strain stiffness and the associated threshold strain parameter. Analytical formulations were implemented to relate stiffness and threshold strain to the mean effective stress and were evaluated through element simulations and boundary-value analyses. Drained triaxial element simulations were performed under confining pressures ranging from 50 to 600&#xa0;kPa to examine the resulting stiffness–strain behavior. Two boundary-value problems, including a triple-anchored excavation and a tunnel excavation, were analyzed to evaluate the implications at the field scale. The results showed that the stress-dependent formulation shifted stiffness-degradation curves toward higher strain levels with increasing confinement and reproduced experimentally observed trends. The modified formulation reduced predicted ground deformations by approximately 5–40% and produced deformation patterns consistent with measured field responses. The results demonstrate that incorporating stress dependency in both stiffness and threshold strain improves deformation prediction consistency with experiments of small-strain constitutive models for geotechnical deformation analysis.</p> Graphical Abstract <p></p>