Recently, some authors have found derivations and applications of the golden ratio in economics science. Based on previous models of Financial Gravity (FG) and generalizing them, this paper proposes the maximization of pure flows after charges as a way for applying the golden ratio in the sales-costs of production ratio in competitive equilibrium, leading to an optimal unitary charge of 0.2361… with many economic applications in monetary economics as well as in finance, public economics and taxation, migration flows, VAT on goods and services and commercial trading. Other applications are also suggested for further research. This paper can be useful for mathematical and applied economists, public financiers, bankers and policy and lawmakers.