The social discount rate is an important tool used to evaluate investment projects and government policies at the regional level. The process of evaluating the contracts for the award of contracts for construction works of some buildings, roads, bridges, installations, etc., the estimated value is calculated based on the lifetime costs, respectively the life cycle costs. The estimated value involves updating income and cost over the life cycle. The authors conclude that the evaluation of the tender using the principle of "lifetime cost" by the contracting authorities. The methodological aspects of estimating the social discount rate are the subject of many scientific studies. In this paper, the authors have systematized different opinions on the methodology for estimating the social discount rate and present arguments on the particularities of its estimation for the evaluation of bids by contracting authorities. The study offers decision-makers suggestions for adjusting the predetermined social discount rate, in order to give a more accurate assessment of the economic and social benefits. The results of the study are relevant for regional and local authorities in developing countries, such as the Republic of Moldova, Ukraine, Georgia, which implement the principles of sustainable development in the public procurement system.