There are various reasons for replacing a helmet. With children, a new helmet is usually necessary because the child has grown and the circumference of their head has increased.
The following applies to helmets for both children and adults: After a fall from a horse, the helmet should be replaced.
Even if you don't see any damage to the helmet, the material may have developed small, fine cracks - perhaps invisible under the lining. In the event of another fall, the helmet will break in these places, instead of protecting the rider's head. This can lead to additional injuries. Even without falls or with an unchanged head circumference, a riding helmet should be replaced every 10 years at most, but preferably after five. Every material wears out over time. This is especially true for helmets, which are exposed to different temperatures and weather conditions.