Normally, California requires both spouses to pay equal shares in support of their child's extracurricular activities. That being said, a court will sometimes consider a different apportionment of those financial obligations if circumstances indicate that it might be more appropriate to require a greater child support obligation from one party. This does not necessarily mean that a court will grant additional child support in each case, but it does illustrate how some requests to modify existing child support orders might be presented.
Under section 4062, the California Family Code generally recognizes that additional child support can be added under certain circumstances. Things that might reasonably be necessary for a child's education or training for employment skills are included on that list. Also included are costs related to a child's educational or other special needs. Perhaps most importantly, section 4062 allows each spouse to present documentation that might demonstrate how it might be more appropriate to require the other spouse to pay a greater percentage for extracurricular activities.
It's important for you to know that a California family law attorney can present your argument to the court for additional support using these additional regulations. A good example of this might be a child who had been training for many years under the guidance of a tutor to play a musical instrument while the parent's marriage was still intact. An attorney might argue that it might be in the child's best interests to require the parent with a significantly greater income to continue paying for the bulk of those expenses.
Alternatively, an attorney representing the spouse with greater income might argue that the child has since lost interest in playing the instrument. Or there may be some other mitigating circumstances regarding their finances that may place an undue burden on that spouse.
Source: California Legislature - leginfo.ca.gov, "Family code section-4062," accessed July 23, 2015