How do you work a horse that overbends to its soft side in dressage?

A horse that overbends to its soft side — bending excessively at the neck in the direction of its natural flexibility while the body remains relatively straight and the outside shoulder falls through — is showing the characteristic pattern of a horse that has learned to evade genuine bend by substituting neck flexibility for body flexibility. This overbending evasion is actually more common and more problematic than simple stiffness because it feels to the rider like the horse is bending when it is actually avoiding the genuine engagement of the inside hind leg that correct bend requires. The correction requires limiting the inside rein — taking it out of the equation as much as possible, because the inside rein is what the horse uses to produce the excessive neck bend — while developing the outside rein's ability to maintain the horse's balance and the inside leg's ability to create genuine body bend. The outside rein is the primary tool for correcting overbending: a firm, consistent outside rein that does not allow the horse to overbend through the neck while maintaining contact prevents the evasion while the inside leg works to create genuine lateral movement through the body. Shoulder-in is again a key exercise, but ridden with particular attention to maintaining a consistent outside rein rather than allowing the horse to drop through the outside shoulder as it often will when the overbending evasion is corrected. The rider must also be attentive to their own inside rein use: the instinct to ask for more bend with the inside rein when the horse's body is not bending is counterproductive with this type of horse and reinforces the very evasion being corrected. Less inside rein, more outside rein, and more inside leg is the general prescription for correcting the overbending horse.