Despite the fact that more than ten years have passed since the rules for domestic systemically important banks (D-SIBs) were developed, the issues of identification of systemically important banks (SIB) and their regulation remain relevant today. Of particular interest is the possibility of forming uniform criteria for identifying systemically important banks within the framework of regional economic associations. The study is aimed at studying the prerequisites and fundamental possibilities of creating common criteria for classifying banks of the participating countries (Kazakhstan, Belarus, Russia) as SIB at the level of the Eurasian Economic Union (EAEU) through a clusterization approach. Clustering methodologies using Euclidean distance metrics and the Hamming model allowed for an initial study on the potential of the participating countries to develop common criteria for the SIB of the EAEU Union. The results of the analysis showed that the participating countries have the potential and some prerequisites for the development of common criteria within the union. However, it was found that the systemically important banks of the participating countries often change the level, since the criteria are not stable. Therefore, when forming uniform criteria, this point should be taken into account and criteria should be developed that are not approximated with each other, and similar features are significantly distinctive. The study consists of two parts, this work is the first part.