In California, child support is usually paid by the non-custodial parent to the custodial parent, as a contribution to the costs of child rearing. The custodial parent is the parent with whom the child primarily lives. When there is a joint custodial living arrangement, and the child lives with both parents equally, the law states that the parent with a lower income may still be entitled to child support. California sets the guidelines for the amount of child support due based, in part, on a certain formula: 1 – gross income of both parents, 2 – amount of time spent with the non-custodial parent, 3 – cost of childcare including health insurance, and 4 – living situation taking other children into account.