Most states have child support guidelines in their statutes—often in the statutes collected in the state’s family code. These child support guidelines provide percentages and methods of calculating child support payments based on the number of children; the parents’ incomes and financial resources; the income and needs of the custodial parent; the needs of the children, including any special needs; and the standard of living for the children before the parents’ divorce or separation. The child support guidelines are just guidelines, and the court generally has discretion to order more or less child support based on the best interest of the children.

In California, child support guidelines are established by state law and are primarily found in the California Family Code. These guidelines use an algebraic formula that takes into account both parents' incomes, the amount of time each parent spends with the child (time-share), and other relevant factors such as taxes, health insurance premiums, mandatory union dues, retirement contributions, and the cost of sharing daycare and uninsured health-care costs. The guidelines aim to provide a standard of support that maintains the children's well-being, factoring in the high cost of living in California. While these guidelines are presumed to be correct, courts have the discretion to deviate from them if special circumstances exist that would make the guideline amount unjust or inappropriate in a particular case. Such deviations must be justified by the court with written findings that consider the best interests of the children.