A technical assistance mission assisted the National Statistical Office of Mongolia (NSO) in improving methods for the compilation of national accounts. The mission recommended that the NSO compiles the chain-linked time series of quarterly GDP instead of using the fixed-base approach. During the mission, the experimental chain-linked time series were compiled with the reference year 2015. Chained-linked time series undoubtedly have a great advantage over the use of a fixed base year, since they consider the updated structure of the economy and provide more reliable results that will be used for domestic policymaking and international surveillance.