So far, research into multinational bank’ overseas expansion has focused on foreign direct investment in the financial services industry. However, this study focused its existing theories on multinational banks on decision-making related to the type of overseas advancement of local financial institutions. For research, four environmental factors were considered: the scale of foreign direct investment, the scope of financial services that can be provided according to the rules of the host country, the corporate tax rate of the host country, and the level of development of the host country’s banking industry. Through Kotra, data on the total amount of claims from 2010 to 2014 and the regulatory status for the country’s financial industries were obtained. Hypothesis are built around theories and survey factors and has been demonstrated through regression analysis. Results show that Korean financial institutions tend to expand as legally independent subsidiaries where the corporate tax rate of the host country is relatively low. Contrary to the previous studies based on the U.S. banking corporates, results show that Korean banks tend to expand in forms of branches to the host countries with high level of banking system development.