You may have some very definite ideas about what your ex should or shouldn't be using the child support you pay to cover.
Unfortunately, many of those ideas may be wrong. Child support isn't just designed to cover the bare necessities -- it goes for a broad variety of household expenses when that household includes a child.
In order to better understand what your ex is allowed to use child support to cover, you have to first understand how the court determines what child support you pay.
How child support is determined
Child support is generally figured according to a computation. The court looks at the lifestyle your child would have had if you and the other parent had stayed together and tried to recreate the lifestyle as closely as possible. While that may seem unfair, the court's interest is in providing for the child's standard of living -- not the parents'.
Then, support is calculated as a percentage of each parent's income and based off of how long every month each parent has the child in his or her physical custody. If the time is fairly even, the parent with the higher income will usually end up paying a small support designed to keep the child's life on an even keel no matter which parent he or she is staying with. If the time with one parent is disproportionate to the time spent with another, the payment will increase accordingly.
How child support can be used
Child support is designed to help cover the living expenses of the child. As such, it isn't unreasonable for part of the child support to go toward commonly used things, like rent or electricity, even if those things also happen to benefit the other parent. From the court's point of view, the fact that it incidentally benefits the other parent is really irrelevant.
Child support can also cover a child's hobbies, like dance class or gymnastics, medication, therapy visits, field trips, school supplies, entertainment expenses and babysitters. All of those things are directly related to the expense of raising a child in today's world.
If you believe that your child support payment is unfairly calculated, the best approach is to take your complaint to the court -- but don't try to argue that any of the above expenses aren't valid.
Source: FindLaw, "What Does Child Support Cover?," accessed Feb. 09, 2018