This paper contributes to the literature on the policy trilemma by evaluating potential policy combinations for the original BRICS within the framework of the Impossible Trinity. It also introduces a novel modelling approach that defines a boundary for the linear combination of variables associated with the policy trilemma. The findings reveal that the trilemma emerges from the interplay of these three policy dimensions. Given the global influence of the BRICS countries, the results suggest that, if they maintain a fixed exchange rate system, they will likely have to sacrifice either free capital movement or independence from monetary policy. This loss of flexibility could be particularly detrimental, considering their significant international influence and their role as major recipients of capital flows for trade and financial transactions. Consequently, the optimal policy combination for BRICS is free capital flow, monetary independence, and a flexible exchange rate.