Child support is calculated using one of three main models: Income Shares (used by 41 states), Percentage of Income (used by 6 states), or the Melson Formula (used by 3 states). The Income Shares model considers both parents' incomes to determine what would have been spent on the child if the family were together. Percentage of Income applies a flat percentage to the non-custodial parent's income. The Melson Formula first ensures each parent can meet their own basic needs before calculating support.

Gross income typically includes wages, salaries, bonuses, commissions, tips, self-employment income, investment income, rental income, retirement/pension benefits, Social Security benefits, disability payments, unemployment compensation, and alimony received. Some states use net income (after taxes) while others use gross income (before taxes). Certain deductions may be allowed, such as taxes, mandatory retirement contributions, and health insurance premiums.

Yes, child support orders can be modified when there's a significant change in circumstances. Common reasons include: substantial change in either parent's income (typically 15-25% or more), change in custody or parenting time arrangements, child's changing needs (medical, educational), remarriage affecting finances, or changes in applicable laws. You'll need to file a motion with the court to request a modification.

In most states, child support continues until the child turns 18 or graduates from high school (whichever is later), typically with a cutoff around age 19-21. Some states extend support through college (usually until age 21-23). Support may also end earlier if the child becomes emancipated, joins the military, or gets married. Special needs children may receive support indefinitely.

If the other parent fails to pay court-ordered child support, you have several enforcement options: Contact your state's child support enforcement agency, request wage garnishment, file a motion for contempt of court, or request liens on property/assets. Consequences for non-payment can include driver's license suspension, passport denial, tax refund interception, and in severe cases, jail time. Keep records of all missed payments.

Yes, custody significantly affects child support calculations. When one parent has primary custody (typically 70%+ of overnights), the other parent usually pays more support. With shared/joint custody (where each parent has significant time, often 30-50%), support is typically reduced because both parents are directly paying for the child's expenses during their time. Most states have specific overnight thresholds that trigger shared custody formulas.