There is no legal definition for extra-curricular activities--not everything is an extra-curricular activity. As such, there is room for ambiguity and interpetation. If your husband and his ex-wife can't work this out between them, it may end up in court, where the judge will interpet what is meant. Based on my experience, the most likely interpretation would be all required costs of the activity(ies): so not just fees, but also the equipment (like uniforms, gloves, shoes) which a child must have to participate. It would probably not encompass voluntary amounts, like gifts for coaches. However, that's just the most common interpretation; since there is no set or definitive interpretation, the judge in this matter would be free to come to a different interpretation, if this ends up in court.