California law demands that each biological parent financially support her child, but a stepparent isn't required to support a stepchild unless the stepparent legally adopts that child, effectively replacing the biological parent. However, a stepparent's income can influence the amount of child support a biological parent must pay under certain circumstances.
California law demands that parents support their children. The law presumes that parents married at the time of conception or birth are the biological parents. However, if they're unmarried when the child is born, a demand for child support from the father will typically require proof of paternity. Once the law establishes parentage, the parent must typically provide support to his child until the child reaches 18, California's age of majority.
The amount of child support owed by each parent is determined by a formula described in the California Family Code, Section 4055. In a nutshell, the court allocates a certain amount of both parties' income for child support, then divides it among the two, adjusting each party's percentage based on the high earner's net income and the amount of time she will be primarily responsible for the child. Typically, the amount of net income required for child support will increase based on the number of children. However, these amounts may fluctuate based on the amount of time that each individual parent will be spending with the child. Although divorcing couples may come to an agreement about child support without the court's help, the court still needs to approve this arrangement in order to protect the child's interests.
Impact of Stepparent
A parent can ask the court to modify the child support amount if circumstances have significantly changed, such as when one parent's income dramatically increases or decreases or when the parents' time spent with the children changes considerably. While a stepparent is not obligated to pay child support for his new spouse's children, a stepparent's income may constitute a significant financial change that impacts his spouse's support requirements. For instance, if the stepparent owns a home or other assets that reduce his spouse's living expenses, the court may find that the spouse has more money available for child support and decide to adjust the amount the spouse must pay or be paid. If children are born of the new marriage, increasing the financial burden on the remarried spouse, the court may also decide to reduce the remarried spouse's payment requirements.
Adoption can change the rules regarding stepparents and child support. A stepparent adoption will typically terminate not only the parental rights, but also the parental support obligations of the biological parent being replaced. When a stepparent legally adopts the child of her spouse, the stepparent takes on the same legal support obligations as a biological parent.