Today, the most promising and effective method of quality control of the continuously cast billets is electromagnetic stirring of the melt. In this case, an important component is the effect of the stirring on the jet in the nozzle. Moreover, as research has shown, this method is highly dependent on the configuration of the inner channel of the nozzle. Research have shown that positive or negative taper of the inner surface of the nozzle allows to obtain different results after applying EMS. Taper control completely changes the pattern of the melt flow and its deceleration in the mold, especially when it is casting of large billets. The results of the research show that minor changes in the taper of the nozzle significantly increase the effect of EMS implementation, which is observed already at 0.27 % of positive the taper and increases to 0.54%.