In recent years,traditional banks in Indonesia have faced various challenges that require banks to have a good level of health to survive. Although it is logically assumed that BUKU IV is the best performer among other BUKU groups due to its large core capital,it needs to be proven statistically. Therefore, this study aims to examine the impact of Mobile Banking Transaction on Net Interest Margin of the two largest BUKU groups, namely BUKU III and BUKU IV,and compare the two results.This study uses four independent variables: NPL, DUMMY COVID. MoTrans,and CASA.