Fatigue life prediction under a requested failure probability is essential to the modern engineering design process. Hence, the validation of multiaxial life prediction models is important with regard to not only the median fatigue lives but also their ability to estimate the failure probability. Herein, the concept of life-dependent material parameters is enhanced by introducing the fatigue life scatter assessment methodology. Aiming to analyze the ability of the life-dependent material parameter concept to calculate the failure probability distribution, we verified this concept’s new ability on a set of stress-based fatigue criteria and new experimental results on 7075-T651 aluminum alloy.