The current study seeks to provide an intellectual framework that deals with the concepts related to both the parallelism of the capital cost structure and the financial failure in banks. The study was based on a main problem: Does the parallelism of the capital cost structure between the cost of ownership and the cost of debt in commercial banks have a role in mitigating or limiting financial failures? In addition, a set of questions about the relationship and impact between the parallelism of the cost of capital structure and the financial failure of the commercial banks surveyed. The study also used several financial and statistical methods to analyze the historical data of the study sample banks, which numbered (10) commercial banks registered in the Iraq Stock Exchange for the period from (2005 to 2021) and to know the relationships between the study variables. The most important conclusion is that any change in the parallelism structure of the cost of capital, with an increase or decrease, will lead to an opposite direction change in financial failure, and vice versa. The most important of which is that bank managements, if they want to succeed in their work, must work on parallelism between the structure of the cost of ownership and the structure of the cost of debt in financing their investment activities and operations.