Gripping under the belt in the end phase of a throwing technique is allowed if the opponent is already in ne-waza. If the throwing technique is interrupted, gripping under the belt is a ne-waza action.
The gripping under the belt in the end phase of a throwing technique like with soto-makikomi continuing through ushiro-gesa-gatame or ura-gatame is allowed. The grip under the belt that becomes an essential part of the throw is not allowed. Judoka are still not allowed to grip under the belt to throw.