International companies need to compensate expatriates in relative proportions to the sacrifices they make to encourage them to accept overseas assignments in countries with harsh working conditions. The scaling of the foreign-service premium allowance problem is addressed as a multi-criteria decision-making problem. This paper presents a unique application of Grey System Theory to the compensation and benefit section of human-resource management. Firstly, this paper presents a hierarchical diagram to evaluate a company’s overseas branches for scaling the compensation of expatriates. Secondly, an unconventional hybrid method for group decision-making with uncertainty is presented. The hybrid method, Stepwise Weight Analysis Ratio Assessment weighting method and the Grey Relational Analysis with grey numbers, is applied to scale the foreign-service premium allowance and rank overseas branches of a company. The research results obtained are from a case study of the solutions to an international company, which was satisfying for both top management and staff union.