The sustainability of companies in the long term depends on the cost of financing. Given that the behavior of this variable originates from the monetary policy of the central banks on the interest rate, this work takes as a proxy, the cost of Colombian business indebtedness, the Reference Banking Indicator (IBR), which reflects the minimum rate at which banks are willing to offer resources. In order to describe the behavior of the IBR, its autocorrelation and relationship with the rates of the main American economies with which it has commercial relations are analyzed: United States, Mexico, Brazil, Chile and Peru. After making multiple estimates, the empirical evidence shows the greatest fit in 12 ARIMAX-IGARCH models, the findings indicate that changes in the monetary policy rates of commercially close countries determine the cost of debt for Colombian companies. © 2024, Associacao Iberica de Sistemas e Tecnologias de Informacao. All rights reserved.