Child support in California is based upon a formula that takes into consideration the amount of time each parent spends with each child (the custodial schedule) and the net income of each party. The court in our office use the same state-approved software (DissoMaster). We input the gross income and all the deductions for each parent and also the child custody schedule and the software determines the support to be paid by one or the other. Often the higher income earner pays the lower income earner child support which lasts until the child reaches the age of 18 or 19 and is still enrolled in high school or is emancipated or dies. But if the parent with the majority of custody is the higher wage earner, the lower income earner may be required to pay child support-but it depends upon the circumstances. Both parents has a duty to support their children.